Polishing liquid composition

ABSTRACT

A polishing liquid composition includes composite oxide particles containing cerium and zirconium, a dispersing agent, and an aqueous medium. A powder X-ray diffraction spectrum of the composite oxide particles obtained by CuKα1 ray (λ=0.154050 nm) irradiation includes a peak (first peak) having a peak top in a diffraction angle 2θ (θ is a Bragg angle) range of 28.61 to 29.67°, a peak (second peak) having a peak top in a diffraction angle 2θ range of 33.14 to 34.53°, a peak (third peak) having a peak top in a diffraction angle 2θ range of 47.57 to 49.63°, and a peak (fourth peak) having a peak top in a diffraction angle 2θ range of 56.45 to 58.91°. A half-width of the first peak is 0.8° or less.

TECHNICAL FIELD

The present invention relates to a polishing liquid composition used,e.g., in chemical-mechanical polishing (CMP) performed in themanufacturing process or the like of a semiconductor device or apolishing treatment performed in the manufacturing process or the likeof a precision glass product, a product associated with a display, etc.Moreover, the present invention relates to a polishing method using thepolishing liquid composition, a method for manufacturing a glasssubstrate, and a method for manufacturing a semiconductor device.

BACKGROUND ART

For example, composite oxide particles containing cerium and zirconiumhave been used to polish an oxide film (e.g., a silicon oxide film)constituting a semiconductor device, base materials of the followingglass substrates: a base material of a chemically tempered glasssubstrate such as an aluminosilicate glass substrate; a base material ofa crystallized glass substrate such as a glass-ceramic substrate; and abase material of a synthetic quartz glass substrate used as a photomasksubstrate, or a glass surface or the like of a liquid crystal displaypanel (see, e.g., Patent Documents 1 and 2).

In order to solve the problems of scratches and dust that arise whenpolishing is performed with a polishing liquid composition includingcerium oxide particles as an abrasive, the polishing liquid compositiondescribed in Patent Document 1 includes composite oxide particles inwhich the secondary particles have an average particle size of 5 μm orless, instead of the cerium oxide particles as an abrasive. Thematerials of the composite oxide particles include a cerium compound(e.g., CeCl₃) and a zirconia compound (e.g., ZrOCl₂). The oxidationnumber of cerium in the cerium compound is 3, and the oxidation numberof zirconia in the zirconia compound is 4. The composite oxide particlesmay be prepared in the following manner.

A cerium compound, a zirconium compound, and ammonia are allowed toreact in an aqueous solution to form a water-insoluble compound issubjected to oxidation, filtration, and centrifugal separation, so thata coprecipitate is obtained. This coprecipitate is cleaned repeatedlywith ultrapure water etc., dried, and then heat-treated in an oven at anatmosphere temperature of 300° C. or more, thereby providing thecomposite oxide particles.

On the other hand, the polishing liquid composition described in PatentDocument 2 includes composite oxide particles that are produced withouta calcining process. Patent Document 2 discloses that this polishingliquid composition can form a surface with high surface accuracy,increase the polishing rate despite a small particle size of thecomposite oxide particles, and suppress damage such as scratches. Thematerials of the composite oxide particles include a cerium compound anda zirconium compound. The oxidation number of cerium in the ceriumcompound is 3 or 4, and the oxidation number of zirconium in thezirconium compound is 4.

-   Patent Document 1: JP 2001-348563 A-   Patent Document 2: Japanese Patent Number 3782771

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

However, polishing with the above polishing liquid compositions canneither ensure a sufficient polishing rate nor reduce scratches.

The present invention provides a polishing liquid opposition capable ofpolishing an object to be polished at a higher speed, a polishing methodusing this polishing liquid composition, a method for manufacturing aglass substrate, and a method for manufacturing a semiconductor device.

Means for Solving Problem

A polishing liquid composition of the present invention includescomposite oxide particles containing cerium and zirconium, a dispersingagent, and an aqueous medium. A powder X-ray diffraction spectrum of thecomposite oxide particles obtained by CuKα1 ray (λ=0.154040 nm)irradiation includes a peak (first peak) having a peak top in adiffraction angle 2θ (θ is a Bragg angle) range of 28.61 to 29.67°, apeak (second peak) having a peak top in a diffraction angle 2θ range of33.14 to 34.53°, a peak (third peak) having a peak top in a diffractionangle 2θ range of 47.57 to 49.63°, and a peak (fourth peak) having apeak top in a diffraction angle 2θ range of 56.45 to 58.91°. Ahalf-width of the first peak is 0.8° or less. When there is at least onepeak of a peak a₁ derived from a cerium oxide and a peak a₂ derived froma zirconium oxide in the powder X-ray diffraction spectrum, both heightsof peak tops of the peaks a₁, a₂ are 6.0% or less of a height of thepeak top of the first peak, where the peak top of the peak a₁ lies in adiffraction angle 2θ range of 28.40 to 28.59° and the peak top of thepeak a₂ lies in a diffraction angle 2θ range of 29.69 to 31.60°.

A polishing liquid composition of the present invention includescomposite oxide particles containing cerium and zirconium, a dispersingagent, and an aqueous medium. The composite oxide particles are obtainedby mixing a precipitant and a solution that include a cerium compoundwith an oxidation number of 4 and a zirconium compound with an oxidationnumber of 4, hydrolyzing the cerium compound and the zirconium compound,separating and subsequently calcining the resultant precipitate, andpulverizing the calcined product.

A polishing method of the present invention includes supplying thepolishing liquid composition of the present invention between an objectto be polished and a polishing pad, and polishing the object to bepolished by moving the polishing pad relative to the object to bepolished while the object to be polished is in contact with thepolishing pad.

A method for manufacturing a glass substrate of the present inventionincludes polishing at least one of two principal surfaces of a basematerial of a glass substrate with the polishing liquid composition ofthe present invention.

A method for manufacturing a semiconductor device of the presentinvention includes a thin film formation process of forming a thin filmon one principal surface side of a semiconductor substrate and apolishing process of polishing the thin film with the polishing liquidcomposition of the present invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 1B is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 1C is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 1D is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 2A is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 2B is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 3A is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 3B is a cross-sectional view showing an example of a step in amanufacturing method of a semiconductor device of the present inventionor in a polishing method of the present invention.

FIG. 4A is a partially enlarged cross-sectional view of an evaluationsample used in Examples of the present invention.

FIG. 4B is a plan view of an evaluation sample used in Examples of thepresent invention.

FIG. 4C is an enlarged view of a portion shown in FIG. 4B.

FIG. 5A is a partially enlarged cross-sectional view of an evaluationsample used in Examples of the present invention.

FIG. 5B is a partially enlarged cross-sectional view of an evaluationsample used in Examples of the present invention.

FIG. 5C is a partially enlarged cross-sectional view of an evaluationsample used in Examples of the present invention.

FIG. 5D is a partially enlarged cross-sectional view of an evaluationsample used in Examples of the present invention.

FIG. 6 is a conceptual diagram of a polished evaluation sample.

FIG. 7 is a graph showing changes in a platen driving current value overtime.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

In Embodiment 1, an example of a polishing liquid composition of thepresent invention will be described.

Composite oxide particles constituting the polishing liquid compositionof Embodiment 1 can be expressed, e.g., by the following compositionformula.Ce_(x)Zr_(1−x)O₂where x is a number satisfying 0<x<1, preferably 0.50<x<0.97, morepreferably 0.55<x<0.95, even more preferably 0.60<x<0.93, much morepreferably 0.65<x<0.90, and further preferably 0.70<x<0.90.

In each of the composite oxide particles, a cerium oxide and a zirconiumoxide are uniformly melted together to form a solid phase. The analysisof these composite oxide particles by the X-ray (cu-Kα1 ray, λ=0.154050nm) diffraction method can provide a spectrum in which the followingpeaks are observed.

In the spectrum, at least a peak (first peak) having a peak top in adiffraction angle 2θ range of 28.61 to 29.67°, a peak (second peak)having a peak top in a diffraction angle 2θ range of 33.14 to 34.53°, apeak (third peak) having a peak top in a diffraction angle 2θ range of47.57 to 49.63°, and a peak (fourth peak) having a peak top in adiffraction angle 2 θ range of 56.45 to 58.91° are observed.

From the viewpoint of improving the polishing rate, it is preferablethat the spectrum of the composite oxide particles includes at least apeak (first peak) having a peak top in a diffraction angle 2θ range of28.61 to 29.39°, a peak (second peak) having a peak top in a diffractionangle 2θ range of 33.14 to 34.16°, a peak (third peak) having a peak topin a diffraction angle 2θ range of 47.57 to 49.08°, and a peak (fourthpeak) having a peak top in a diffraction angle 2θ range of 56.45 to58.25°. It is more preferable that the spectrum of the composite oxideparticles includes at least a peak (first peak) having a peak top in adiffraction angle 2θ range of 28.61 to 29.25°, a peak (second peak)having a peak top in a diffraction angle 2θ range of 33.14 to 34.04°, apeak (third peak) having a peak top in a diffraction angle 2θ range of47.57 to 48.90°, and a peak (fourth peak) having a peak top in adiffraction angle 2θ range of 56.45 to 58.02°. It is even morepreferable that the spectrum of the composite oxide particles includesat least a peak (first peak) having a peak top in a diffraction angle 2θrange of 28.68 to 29.11°, a peak (second peak) having a peak top in adiffraction angle 2θ range of 33.23 to 33.79°, a peak (third peak)having a peak top in a diffraction angle 2θ range of 47.71 to 48.53°,and a peak (fourth peak) having a peak top in a diffraction angle 2θrange of 56.61 to 57.60 °.

It is preferable that a second peak area is 10 to 50% of a first peakarea, a third peak area is 35 to 75% of the first peak area, and afourth peak area is 20 to 65% of the first peak area. From the viewpointof improving the polishing rate, it is more preferable that the secondpeak area is 15 to 45% of the first peak area, the third peak area is 40to 70% of the first peak area, and the fourth peak area is 25 to 60% ofthe first peak area. It is even more preferable that the second peakarea is 20 to 40% of the first peak area, the third peak area is 45 to65% of the first peak area, and the fourth peak area is 30 to 55% of thefirst peak area.

In the spectrum, there may be at least one peak of a peak a₁ derivedfrom the cerium oxide and a peak a₂ derived from the zirconium oxide. Inthis case, from the viewpoint of reducing scratches, both heights of thepeak tops of the peaks a₁, a₂ are 6.0% or less, preferably 3.0% or less,more preferably 1.0% or less, and even more preferably 0% of the heightof the peak top of the first peak.

The peak top of the peak a₁ lies in a diffraction angle 2θ range of28.40 to 28.59°, and the peak top of the peak a₂ lies in a diffractionangle 2θ range of 29.69 to 31.60°. In the present specification, thesevalues of the diffraction angle 2θ range are based on the values of thecerium oxide and the zirconium oxide obtained from the ICDD(international center for diffraction data). Specifically, thediffraction angle 2θ range of 28.40 to 28.59° including the peak top ofthe peak a₁ relates to a cubic cerium oxide. The diffraction angle 2θrange of 29.69 to 31.60° including the peak top of the peak a₂ is basedon 2θ (29.69°) of a tetragonal zirconium oxide and 2θ (31.60°) of amonoclinic zirconium oxide.

The half-width of the first peak is 0.8° or less, but preferably 0.7° orless, more preferably 0.6° or less, even more preferably 0.5° or less,and much more preferably 0.45° or less from the viewpoint of improvingthe polishing rate. As expressed by the Scherrer equation, thishalf-width correlates with the crystallite size. The half-width becomessmaller with an increase in the crystalline size due to crystal growth.

In the composite oxide particles included in the polishing liquidcomposition of this embodiment, the cerium oxide derives from a ceriumcompound with an oxidation number of 4 and the zirconium oxide derivesfrom a zirconium compound with an oxidation number of 4, as will bedescribed later. For this reason, the cerium oxide and the zirconiumoxide are uniformly melted together to form a solid phase, and thus theabove X-ray diffraction spectrum may be observed. When the cerium oxideof the composite oxide particles derives from a cerium compound with anoxidation number of 3, as in the case of the composite oxide particlesincluded in the polishing liquid composition of Patent Document 1, asolid phase such that the cerium oxide and the zirconium oxide areuniformly melted together cannot be formed sufficiently. Consequently,at least one peak of the peak a₁ derived from the cerium oxide and thepeak as derived from the zirconium oxide is observed.

The X-ray diffraction spectrum of the composite oxide particles includedin the polishing liquid composition of this embodiment shows that thehalf-width of the first peak is small and the first peak is very sharp.This is because the crystallite size of the solid phase may beincreased, namely the crystallinity may be improved by sufficientcalcination of the composite oxide particles during the manufacturingprocess, as will be described later. In contrast, since the compositeoxide particles included in the polishing liquid composition of PatentDocument 2 are not calcined sufficiently during the manufacturingprocess, the crystallinity of the solid phase is not satisfactory. Thus,the X-ray diffraction spectrum shows that the half-width of the firstpeak is large and the first peak is broad.

As described above, the polishing liquid composition of this embodimentincludes the composite oxide particles having a solid phase with highcrystallinity, in which the cerium oxide and the zirconium oxide areuniformly melted together. Therefore, the polishing liquid compositionof this embodiment is capable of polishing the object to be polished ata higher speed than the conventional polishing liquid composition.

From the viewpoint of improving the polishing rate, the molar ration(Ce/Zr) of atoms in the composite oxide particles is preferably (99/1)to (5/95), more preferably (97/3) to (16/84), even more preferably(35/5) to (40/60), much more preferably (94/6) to (50/50), and furtherpreferably (93/7) to (60/40).

From the viewpoint of reducing scratches, the atomic ration x of Ce toZr in the composite oxide (Ce_(x)Zr_(1−x)O₂) particles is preferably0.60 to 0.93, more preferably 0.65 to 0.90, and even more preferably0.70 to 0.90.

From the viewpoint of improving the polishing rate, the volume mediandiameter (D50) of the composite oxide particles is preferably 30 nm ormore, more preferably 40 nm or more, and even more preferably 50 nm ormore. From the viewpoint of improving the dispersion stability of thecomposite oxide particles in the polishing liquid composition, D50 ispreferably 1000 nm or less, more preferably 500 nm or less, and evenmore preferably 250 nm or less. Accordingly, the volume median diameter(D50) of the composite oxide particles is preferably 30 to 1000 nm, morepreferably 40 to 500 nm, and even more preferably 50 to 250 nm.

In the present specification, the volume median diameter (D50) indicatesa particle size at which the cumulative volume frequency calculatedbased on the volume fraction of the particles from a smaller particlesize side reaches 50%. The volume median diameter (D50) is obtained as amedian diameter on the volume basis measured with a laserdiffraction/scattering particle size distribution analyzer (LA-920manufactured by HORIBA Ltd.).

From the viewpoint of improving the polishing rate, the average primaryparticle size of the composite oxide particles is preferably 10 nm ormore, more preferably 20 nm or more, and even more preferably 30 nm ormore. From the viewpoint of improving the specular state of the polishedsurface as a result of polishing the object to be polished, the averageprimary particle size of the composite oxide particles is preferably 200nm or less, more preferably 150 nm or less, and even more preferably 100nm or less. Accordingly, the average primary particle size of thecompositie oxide particles is preferably 10 to 200 nm, more preferably20 to 150 nm, and even more preferably 30 to 100 nm.

In the present specification, the average primary particle size (nm)indicates a particle size (converted to spherical diameter) determinedby the following equation using a specific surface are S (m²/g) that iscalculated with a BET (nitrogen adsorption) method.Average primary particle size (nm)=820/S

From the viewpoint of improving the polishing rate, the content of thecomposite oxide particles in the polishing liquid composition ispreferably 0.1 wt % or more, more preferably 0.2 wt % or more, even morepreferably 0.4wt % or more, and much more preferably 0.5 wt % or more.From the viewpoint of improving the dispersion stability and reducingthe cost, the content of the composite oxide particles is preferably 8wt % or less, more preferably 5 wt % or less, even more preferably 4 wt% or less, and much more preferably 3 wt % or less. Accordingly, thecontent of the composite oxide particles is preferably 0.1 to 8 wt %,more preferably 0.2 to 5 wt %, even more preferably 0.4 to 4 wt %, andmuch more preferably 0.5 to 3 wt %.

The composite oxide particles may be either a commercially availableproduct or an in-house product. Next, an example of a method forproducing the composite oxide particles will be described.

The composite oxide particles can be produced by mixing a precipitantand a solution that includes the cerium compound with an oxidationnumber of 4 (also referred to as a cerium (IV) compound in thefollowing) and the zirconium compound with an oxidation number of 4(also referred to as a zirconium (IV) compound in the following),hydrolyzing the cerium (IV) compound and the zirconium (IV) compound,separating and subsequently calcining the resultant precipitate, andpulverizing the calcined product.

The solution including the cerium (IV) compound and the zirconium (IV)compound may be prepared, e.g., by dissolving a water-soluble cerium(IV) compound such as cerium nitrate and a water-soluble zirconium (IV)compound such as zirconium nitrate in solvents such as waterindividually, and mixing these two solutions.

When a precipitant (basic solution) is added to the solution includingthe cerium (IV) compound and the zirconium (IV) compound, the cerium(IV) compound and the zirconium (IV) compound are hydrolyzed, and aprecipitate is generated. It is preferable that the precipitant is addedwhile stirring the solution including the cerium (IV) compound and thezirconium (IV) compound. Examples of the precipitant include an ammoniasolution, an alkali hydroxide solution such as a sodium hydroxidesolution or a potassium hydroxide solution, a carbonate solution ofsodium, potassium, or ammonia, and a bicarbonate solution. Inparticular, the precipitant is preferably an aqueous solution ofammonia, sodium hydroxide, or potassium hydroxide, and more preferablyan ammonia aqueous solution. The normality of the precipitant ispreferably about 1 to 5N, and more preferably about 2 to 3N.

From the view point of providing the composite oxide particles in whichthe cerium oxide and the zirconium oxide are highly incorporated to forma solid solution, the pH of a supernatant fluid obtained by adding theprecipitant to the solution including the cerium (IV) compound and thezirconium (IV) compound is preferably 7 to 11, and more preferably 7.5to 9.5.

The mixing time of the solution including the cerium (IV) compound andthe zirconium (IV) compound with the precipitant is not particularlylimited, but is preferably 15 minutes or more, and more preferably 30minutes or more. The reaction between the solution including the cerium(IV) compound and the zirconium (IV) compound and the precipitant can beperformed at any appropriate temperature such as room temperature. Theprecipitate generated by mixing the solution including the cerium (IV)compound and the zirconium (IV) compound with the precipitant can beseparated from the mother liquor by decantation, drying, filtration,and/or a general solid-liquid separation technique such as centrifugalseparation. The resultant precipitate is then cleaned with water or thelike.

A desirable state of the cerium (IV) compound in the solution is thatthe cerium (IV) compound is merely added to the aqueous medium. However,the cerium compound containing cerium with an oxidation number of 3 maybe electrolytically oxidized in the aqueous medium so that the trivalentcerium is changed to tetravalent cerium. The cerium (IV) compound isincluded preferably in an amount of 85 wt % or more, more preferably 87wt % or more, even more preferably 90 wt % or more, and much morepreferably 95 wt % or more of the total amount of the cerium compound.

Specifically, the cerium (IV) compound may be water-soluble salts suchas cerium (IV) sulfate, cerium (IV) tetraammonium sulfate, and cerium(IV) diammonium nitrate. The reason for using the salt of cerium with anoxidation number of 4 is that it can be hydrolyzed easily compared tothe salt of cerium with an oxidation number of 3 and also is suitablefor simultaneous hydrolysis with the zirconium (IV) compound (e.g., asalt of zirconium with an oxidation number of 4) in view of thehydrolysis rate.

The zirconium (IV) compound in the solution may be water-solublezirconium (IV) salts such as zirconium oxychloride (zirconyl chloride),zirconium oxysulfate (zirconyl sulfate), zirconium oxyacetate(zirconylacetate), zirconium oxynitrate (zirconyl nitrate), zirconium chloride,zirconium nitrate, zirconium acetate, and zirconium sulfate.

As described above, when both the cerium and the zirconium in thesolution have an oxidation number of 4, and the pH of the solution israised by the addition of a basic solution (precipitant), the cerium(IV) compound and the zirconium (IV) compound are hydrolyzedsubstantially in the same pH range, and cerium hydroxide and zirconiumhydroxide precipitate substantially at the same time, resulting in aprecipitate in which the cerium hydroxide and the zirconium hydroxideare highly mixed with each other. This precipitate is heat-treated, andthen a cerium oxide and a zirconium oxide are uniformly melted togetherto form a solid phase in part of the precipitate. If the oxidationnumber of cerium is 3, the cerium (III) compound and the zirconium (IV)compound are hydrolyzed to cause the precipitation of their hydroxidesin different pH ranges. Therefore, a precipitate in which the ceriumhydroxide and the zirconium hydroxide are not sufficiently mixed isgenerated. Consequently, when this precipitate is heat-treated, a ceriumoxide or a zirconium oxide is generated in part of the precipitate.

When the total amount of the cerium element and the zirconium element inthe solution including the cerium (IV) compound and the zirconium (IV)compound is 100 wt % in terms of oxide, the amount of the cerium elementis preferably 7 to 99 wt %, more preferably 20 to 98 wt %, and even morepreferably 50 to 96 wt % in terms of oxide. The amount of zirconiumelement is preferably 1 to 93 wt %, more preferably 2 to 80 wt %, andeven more preferably 4 to 50 wt % in terms of oxide.

From the viewpoint of improving the crystallinity of the solid phase inwhich the cerium oxide and the zirconium oxide are uniformly meltedtogether and ensuring a good polishing rate, the calcination temperatureof the precipitate is preferably 900 to 1500° C., more preferably 1000to 1400° C. and even more preferably 1100 to 1300° C. Usually, theheating time if preferably 1 to 10 hours, more preferably 2 to 8 hours,and even more preferably 3 to 7 hours. The calcination can be performed,e.g., using a heating means such as a continuous kiln. The calcinationtemperature indicates a temperature of the particle surface and is equalto the atmospheric temperature inside the continuous kiln.

A means for pulverizing the calcined product is not particularly limitedand may be a grinding apparatus such as a ball mill, a bead mill, or anoscillating mill. The conditions of the pulverizing means may be setappropriately so as to form particles that fall in the desired range ofaverage particle sizes or volume median diameter. The grinding media maybe a zirconia ball or the like.

The aqueous medium included in the polishing liquid composition of thisembodiment may be water, a mixed medium of water and a solvent, or thelike. The preferred solvent may be a solvent that can be mixed withwater (e.g., alcohol such as ethanol). In particular, the aqueous mediumis preferably water, and more preferably ion-exchanged water.

The dispersing agent included in the polishing liquid composition ofthis embodiment is preferably soluble in water. It is preferable thatthe water soluble dispersing agent is at least one selected from thegroup consisting of a cationic surface-active agent, an anionicsurface-active agent, a nonionic surface-active agent, and an acrylicacid-based polymer. It is more preferable that the dispersing agent isat least one selected from the group consisting of an anionicsurface-active agent, a nonionic surface-active agent, and an acrylicacid-based polymer. It is even more preferable that the dispersing agentis an acrylic acid-based polymer. The dispersing agent may be eitheradsorbed physically by the surfaces of the composite oxide particles orbonded chemically to the surfaces of the composite oxide particlesbefore it is mixed with the aqueous medium.

Examples of the cationic surface-active agent include an aliphatic aminesalt and an aliphatic ammonium salt.

Examples of the anionic surface-active agent include a fatty acid soap,carboxylate such as alkyl ether carboxylate, sulfonate such as alkylbenzene sulfonate or alkyl naphthalene sulfonate, sulfate such as fattyalcohol sulfate or alkyl ether sulfate, and phosphate such as alkylphosphate.

Examples of the nonionic surface-active agent include an ether type suchas polyoxyethylene alkyl ether, an ether-ester type such aspolyxyethylene ether of glycerin ester, and an ester type such aspolyethylene glycol fatty acid ester, glycerin ester, or sorbitan ester.

The acrylic acid-based polymer may be either a homopolymer or acopolymer. The preferred homopolymer may be a homopolymer having aconstitutional unit (A) derived from a monomer (a) such as acrylic acid,a non-metallic salt of acrylic acid, or acrylic ester. The preferredcopolymer may be a copolymer having a constitutional unit (A) derivedfrom at least one monomer (a) selected from the group consisting ofacrylic acid, a non-metallic salt of acrylic acid, and acrylic ester anda constitutional unit (B) derived from the following monomer (b) or acopolymer having constitutional units (A), each of which is derived fromat least two monomers (a) selected from the group consisting of acrylicacid, a non-metallic salt of acrylic acid ammonium salt or an acrylicacid amine salt. The acrylic acid-based polymer may include one or moreconstitutional units derived from these non-metallic salts of acrylicester.

The non-metallic salt of acrylic acid may be, e.g., an acrylic acidammonium salt or an acrylic acid amine salt. The acrylic acid-basedpolymer may include one or more constitutional units derived from thesenon-metallic salts of acrylic acid.

When the acrylic acid-based polymer is a copolymer, the constitutionalunit (A) included in the copolymer is more than 50 mol % of the totalconstitutional unit, but preferably more than 70 mol %, more preferablymore than 80 mol %, and even more preferably more than 90 mol %.

The monomer (b) has a carboxylic acid (carboxylate) group and contains apolymerizable double bond. Examples of the monomer (b) include itaconicacid, itaconic anhydride, methacrylic acid, maleic acid, maleicanhydride, fumaric acid, fumaric anhydride, citraconic acid, citraconicanhydride, glutaconic acid, vinylacetic acid, allylacetic acid,phosphinocarboxylic acid, α-haloacrylic acid, β-carboxylic acid, saltsof these acids, and methacrylic acid alkyl esters such as methylmethacrylate, ethyl methacrylate, and octyl methacrylate.

When the acrylic acid-based polymer is a salt, it can be produced insuch a manner than an acid-type acrylic acid monomer is polymerizedalone or copolymerized with the monomer (b), and then is neutralizedwith a predetermined alkali. The salt may be, e.g., an ammonium salt ofa copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonicacid.

From the viewpoint of improving the dispersion stability, the acrylicacid-based polymer is preferably at least one selected from the groupconsisting of polyacrylic acid and ammonium polyacrylate, and morepreferably ammonium polyacrylate.

From the viewpoint of improving the dispersion stability, the weightaverage molecular weight of the acrylic acid-based polymer is preferably500 to 50000, more preferably 500 to 10000, and even more preferably1000 to 10000.

In the present specification, the weight average molecular weight iscalculated based on the peaks in a chromatogram that is obtained by agel permeation chromatography (GPC) method under the followingconditions.

-   -   Column: G4000PWXL+G2500PWXL (TOSO CORPORATION)    -   Eluant: (0.2 M phosphate buffer)/(CH₃CN)=9/1 (volume ratio)    -   Flow rate: 1.0 mL/min    -   Column temperature: 40° C.    -   Detector: RI detector    -   Reference material: polyacrylic acid

From the viewpoint of improving the dispersion stability the content ofthe dispersing agent in the polishing liquid composition is preferably0.0005 wt % or more, more preferably 0.001 wt % or more, and even morepreferably 0.002 wt % or more. Moreover, the content of the dispersingagent in the polishing liquid composition is preferably 0.5 wt % orless, more preferably 0.1 wt % or less, and even more preferably 0.05 wt% or less. Accordingly, the content of the dispersing agent ispreferably 0.0005 to 0.5 wt %, more preferably 0.001 to 0.1 wt %, andeven more preferably 0.002 to 0.05 wt %.

Although the above content of each component is applied to the polishingliquid composition in use, the polishing liquid composition of thisembodiment may be preserved and provided in the form of a concentrate aslong as its stability is not impaired. This is preferred because theproduction and transportation costs can be reduced. The concentrate maybe diluted appropriately with the above aqueous medium as needed.

When the polishing liquid composition of this embodiment is in the formof a concentrate, from the viewpoint of reducing the production andtransportation costs, the content of the composite oxide particles ispreferably 2 wt % or more, more preferably 3 wt % or more, even morepreferably 5 wt % or more, and much more preferably 10 wt % or more.From the viewpoint of improving the dispersion stability, the content ofthe composite oxide particles is preferably 50 wt % or less, morepreferably 40 wt % or less, and even more preferably 30 wt % or less.Accordingly, the content of the composite oxide particles is preferably2 to 50 wt %, more preferably 3 to 40 wt %, even more preferably 5 to 30wt %, and much more preferably 10 to 30 wt %.

The polishing liquid composition of this embodiment further may includeat least one type of optional component selected from a pH adjuster, anantiseptic agent, and an oxidizing agent as long as the optionalcomponent does not interfere with the effect of the present invention.

The pH adjuster may be, e.g., a basic compound or an acid compound.Examples of the basic compound include ammonia, potassium hydroxide,water-soluble organic amine, and quaternary ammonium hydroxide. Examplesof the acid compounds include inorganic acid such as sulfuric acid,hydrochloric acid, nitric acid, or phosphoric acid and organic acid suchas acetic acid, oxalic acid, succinic acid, glycolic acid, malic acid,citric acid, or benzoic acid.

The antiseptic agent may be, e.g., benzalkonium chloride, benzethoniumchloride, 1,2-benzisothiazoline-3-one,(5-chloro-)2-methyl-4-isothiazoline-3-one, hydrogen peroxide, orhypochlorite.

The oxidizing agent may be, e.g., peroxides such as permanganic acid andperoxoacid, chromic acid, nitric acid, or salts thereof.

The pH of the polishing liquid composition of this embodiment at 25° C.is not particularly limited, but is preferably 2 to 10, more preferably3 to 9, even more preferably 4 to 8, and much more preferably 4.5 to 7,since the polishing rate can be improved further. In this case, the pHof the polishing liquid composition at 25° C. an be measured with a pHmeter (HM-30G manufactured by DKK-TOA CORPORATION) and is read on the pHmeter 1 minute after dipping an electrode into the polishing liquidcomposition.

Next, an example of a method for producing the polishing liquidcomposition of this embodiment will be described.

The method for producing the polishing liquid composition of thisembodiment is not limited at all. For example, the polishing liquidcomposition may be produced by mixing the composite oxide particles, thedispersing agent the aqueous medium, and the optional component asneeded.

The composite oxide particles can be dispersed in the aqueous medium,e.g., using an agitator such as a homomixer, a homogenizer, anultrasonic disperser, a wet ball mill, or a bead mill. After dispersingthe composite oxide particles in the aqueous medium, if coarse particlesresulting from the aggregation or the like of the composite oxideparticles are present in the aqueous medium, it is preferable that thecoarse particles should be removed by centrifugal separation orfiltration. The composite oxide particles are dispersed preferably inthe presence of the dispersing agent.

Next, a polishing method using the polishing liquid composition of thisembodiment will be described.

In an example of the polishing method using the polishing liquidcomposition of this embodiment, the polishing liquid composition issupplied between the object to be polished and a polishing pad of apolishing apparatus, and the polishing pad is moved relative to theobject to be polished while the object to be polished is in contact withthe polishing pad, thereby polishing the object to be polished.

The polishing pad is attached, e.g., to a polishing platen such as arotary table. The object to be polished is held by a carrier or thelike. The polishing apparatus may be either a double-sided polishingapparatus capable of polishing both principal surfaces of a plate-shapedobject to be polished simultaneously or a single-shaped polishingapparatus capable of polishing only one principal surface of theplate-shaped object to be polished.

(Polishing of a Base Material of a Glass Substrate)

The material of a polishing pad used to polish a base material of aglass substrate is not particularly limited, and any conventionallyknown materials can be used.

Examples of the base material to be polished include quartz glass, sodalime glass, aluminosilicate glass, borosilicate glass,aluminoborosilicate glass, non-alkali glass, crystallized glass, andglassy carbon. Among them, the polishing liquid composition of thisembodiment is suitable for the polishing of the base material of analuminosilicate glass substrate (which is an example of a tempered glasssubstrate), the base material that is turned into a glass ceramicsubstrate (i.e., crystallized glass substrate) by polishing, and thebase material that is turned into a synthetic quartz glass substrate bypolishing. The base material of the aluminosilicate glass substrate hasgood chemical durability and is less susceptible to damage (e.g.,defects in concave portions) caused by alkali cleaning that is performedto remove residual particles from the polished substrate, so that aglass substrate with higher surface quality can be provided. Thesynthetic quartz glass substrate is preferred because of its excellentoptical characteristics such as transmittance.

The shape of the base material of the glass substrate is notparticularly limited. For example, the base material may have a shapewith flat portions such as a disk, a plate, a slab, or a prism and ashape with curved portions such as a lens. The polishing liquidcomposition of this embodiment is suitable particularly for thepolishing of the base material of the glass substrate in the form of adisk or plate.

From the viewpoint of improving the polishing rate, the polishing loadapplied to the base material of the glass substrate by the polishingapparatus is preferably 3 kPa or more, more preferably 4 kPa or more,even more preferably 5 kPa or more, and much more preferably 5.5 kPa ormore. From the viewpoint of improving the quality of the polishedsurface and relieving the residual stress of the polished surface, thepolishing load is preferably 12 kPa or less, more preferably 11 kPa orless, even more preferably 10 kPa or less, and much more preferably 9kPa or less. Accordingly, the polishing load is preferably 3 to 12 kPa,more preferably 4 to 11 kPa, even more preferably 5 to 10 kPa, and muchmore preferably 5.5 to 9 kPa.

The supply rate of the polishing liquid composition varies depending onthe following factors: the sum of the area of a surface of the polishingpad facing the object to be polished and the area of a surface of thebase material of the glass substrate that is to be polished; and thecomposition of the polishing liquid composition. From the viewpoint ofimproving the polishing rate, the supply rate is preferably 0.06 to 5ml/min, more preferably 0.08 to 4 ml/min, and even more preferably 0.1to 3 ml/min per 1 cm² of the surface to be polished.

The number of revolutions of the polishing pad is preferably 10 to 200rpm, more preferably 20 to 150 rpm, and even mote preferably 30 to 60rpm. The number of revolutions of the object to be polished ispreferably 10 to 200 rpm, more preferably 20 to 150 rpm, and even morepreferably 30 to 60 rpm.

(Polishing of a Thin Film During the Manufacturing Process of aSemiconductor Device)

The polishing liquid composition of this embodiment also can be used,e.g., to polish a thin film that is disposed on one principal surfaceside of a semiconductor substrate.

Examples of the material of the semiconductor substrate include anelementary semiconductor such as Si or Ge, a compound semiconductor suchas GaAs, InP, or CdS, and a mixed crystal semiconductor such as InGaAsor HgCdTe.

Examples of the material of the thin film include the followingmaterials constituting a semiconductor device: a metal as aluminum,nickel, tungsten, copper, tantalum, or titanium; a semimetal such assilicon; an alloy containing any of these metals as the main component:a glass material such as glass, glassy carbon, or amorphous carbon; aceramic material such as alumina, silicon dioxide, silicon nitride,tantalum nitride, or titanium nitride; and a resin such as a polyimideresin. In particular, the thin film preferably includes silicon, andmore preferably includes at least one selected from the group consistingof silicon oxide, silicon nitride, and polysilicon, since such a thinfilm can be polished at a high speed. The silicon oxide may be, e.g.,silicon dioxide or tetraethoxysilane (TEOS). The thin film including thesilicon oxide may be doped with elements such as phosphorus and boron.Specific examples of such a thin film include a BPSG(boro-phospho-silicate glass) film and a PSG (phospho-silicate glass)film.

A method for forming the thin film may be selected appropriately inaccordance with the material constituting the thin film. For example, aCVD method, a PVD method, a coating method, and a plating method can beused.

From the viewpoint of improving the polishing rate, the polishing loadapplied to the thin film by the polishing apparatus while the thin filmis polished is preferably 5 kPa or more, and more preferably 10 kPa ormore. From the viewpoint of improving the quality of the polishedsurface and relieving the residual stress of the polished surface, thepolishing load is preferably 100 kPa or less, more preferably 70 kPa orless, and even more preferably 50 kPa or less. Accordingly, thepolishing load is preferably 5 to 100 kPa, more preferably 10 to 70 kPa,and even more preferably 10 to 50 kPa.

The supply rate of the polishing liquid composition varies depending onthe following factors: the sum of the area of a surface of the polishingpad facing the object to be polished and the area of a surface of thethin film that is to be polished; and the composition of the polishingliquid composition. From the viewpoint of improving the polishing rate,the supply rate is preferably 0.01 ml/min or more, and more preferably0.1 ml/min or more per 1 cm² of the surface of the object to bepolished. From the viewpoint of reducing the cost and facilitating thedisposal of liquid wastes, the supply rate of the polishing liquidcomposition is preferably 10 ml/min or less, and more preferably 5ml/min or less per 1 cm² of the surface to be polished. Accordingly, thesupply rate of the polishing liquid composition is preferably 0.01 to 10ml/min, and more preferably 0.1 to 5 ml/min per 1 cm² of the surface tobe polished.

The material or the like of the polishing pad used in the polishingprocess is not particularly limited, and any conventionally knownmaterials can be used. Examples of the material of the polishing padinclude an organic polymer foam such as a rigid polyurethane foam and aninorganic foam. In particular, the rigid polyurethane foam is preferred.

The number of revolutions of the polishing pad is preferably 30 to 200rpm, more preferably 45 to 150 rpm, and even more preferably 60 to 100rpm.

The thin film may have an uneven surface. The thin film with an unevensurface can be produced, e.g., by a) a thin film formation process offorming a thin film on one principal surface side of the semiconductorsubstrate and b) an uneven surface formation process of forming aconcavo-convex pattern on the surface of the thin film that is oppositeto the surface facing the semiconductor substrate. The concavo-convexpattern can be formed by a conventionally known lithography technique orthe like. In some cases, the surface of the thin film that is oppositeto the surface facing the semiconductor substrate may have aconcavo-convex pattern corresponding to a convexo-concave pattern of thelower layer. It is preferable that the conditions such as the polishingload, the supply rate of the polishing liquid composition, the materialof the polishing load, and the number of revolutions of the polishingpad for polishing the thin film with an uneven surface are the same asthose for polishing the above thin film.

The polishing of the thin film of this embodiment is suitable in thecase where a difference in level (H) between the mutually adjacentconvex and concave portions (see FIG. 1C or 3A) is preferably 50 to 2000nm, and more preferably 100 to 1500 nm. The “difference in level (H)”means a distance between the top of the convex portion and the bottom ofthe concave portion, and can be determined with a profile measuringapparatus (HRP-100 manufactured by KLA-Tencor Corporation).

The polishing liquid composition of this embodiment can be applied toany type of polishing during the manufacturing process of thesemiconductor device. Specific examples include (1) polishing performedin the process of forming a buried isolation film, (2) polishingperformed in the process of flattening an interlayer insulating film,(3) polishing performed in the process of forming buried metal wiring(damascene interconnect etc.), and (4) polishing performed in theprocess of forming a buried capacitor.

Examples of the semiconductor device include a memory IC (integratedcircuit), a logic IC, and a system LSI (large-scale integration).

The polishing liquid composition of this embodiment also can be used topolish the base material of a crystallized glass substrate such as aglass-ceramic substrate, the base material of a synthetic quartz glasssubstrate used as a photomask substrate, or the glass surface or thelike of a liquid crystal display panel in addition to the base materialof the glass substrate constituting a hard disk or the like and theinsulating layer constituting the semiconductor device.

Next, the polishing performed in tire process of forming a buriedisolation film during the manufacturing process of the semiconductordevice will be described with reference to the drawings.

As shown in FIG. 1A, a silicon nitride (SiN₄) film 2 is formed, e.g., bya CVD (chemical vapor deposition) method on a silicon dioxide film (notshown) that is obtained by exposing a semiconductor substrate 1 tooxygen in an oxidation furnace. Then, as shown in FIG. 1B, a shallowtrench is formed by a photolithography technique. Next, as shown in FIG.1C, an oxide film (SiO₂ film) 3 for covering the trench is formed, e.g.,by a CVD method using a silane gas and an oxygen gas. The surface of theoxide film 3 that is opposite to the surface facing the semiconductorsubstrate 1 has a convexo-concave pattern with a difference in level H,and this convexo-concave pattern corresponds to the convexo-concavepattern of the lower layer. Subsequently, the oxide film 3 is polisheduntil its surface is substantially flush with the surface of the siliconnitride film 2 by a CMP method (see FIG. 1D). The polishing liquidcomposition of this embodiment is used for this polishing by the CMPmethod.

Next, the polishing performed in the process of flattening an interlayerinsulating film during the manufacturing process of the semiconductordevice will be described with reference to the drawings.

As shown in FIG. 2A, a metal film 19 (e.g., an Al thin film) is formed,e.g., by sputtering on one principal surface side of a semiconductorsubstrate 11. In the example of FIG. 2A, a source 12 and a drain 13 areformed as impurity diffusion regions doped with impurities in thesemiconductor substrate 11. In FIG. 2A, the following componentsunderlie the metal film 19; a gate electrode 15 whose surface issilicided; sidewalls 14 located at both ends of the gate electrode 15;insulating layers 16, 17 made of SiO₂ or the like; and a tungsten plug18 that penetrates the insulating layers 16, 17 to make an interlayerconnection between the metal thin film 19 and the gate electrode 15.

Next, as shown in FIG. 2B, the metal thin film 19 is patterned by aphotolithography technique and a dry etching technique, so thatextraction electrodes 20 are formed. Thus, a CMOS structure iscompleted.

Next, as shown in FIG. 3A, an oxide film (SiO₂ film) 21 is formed, e.g.,by a CVD method using a silane gas and an oxygen gas. The surface of theoxide film 21 that is opposite to the surface facing the semiconductorsubstrate 11 has a convexo-concave pattern with a difference in level H,and this convexo-concave pattern corresponds to the convexo-concavepattern of the lower layer. Subsequently, the oxide film 21 is polishedby a CMP method (see FIG. 3B). The polishing liquid composition of thisembodiment is used for this polishing by the CMP method.

As described above, the present invention can provide a polishing liquidcomposition capable of polishing an object to be polished at a higherspeed, a polishing method using this polishing liquid composition, amethod for manufacturing a glass substrate, and a method formanufacturing a semiconductor device.

Embodiment 2

In Embodiment 2, another example of a polishing liquid composition ofthe present invention will be described.

The polishing liquid composition of this embodiment includes awater-soluble organic compound that contributes to the formation of apolished surface with high flatness in addition to the above describedcomposite oxide particles.

The polishing liquid composition of this embodiment can provide not onlya polished surface with high flatness by including the water-solubleorganic compound as an additive, but also a high polishing rate by usingthe composite oxide particles containing cerium and zirconia as abrasiveparticles, which have never been known before.

The reason for this can be considered as follows. In the polishingliquid composition of this embodiment, the composite oxide particlescontaining cerium and zirconium can act as abrasive grains for polishingthe object to be polished at a high speed, as will be described later.When the polishing liquid composition of this embodiment is supplied tothe surface to be polished, the water-soluble organic compounds adsorbsto the surface to be polished, the water-soluble organic be polished,and thus forms a coating. This coating interferes with the action of thecomposite oxide particles on the surface to be polished. The coating isbroken after a large polishing load is applied to the surface to bepolished, and then this surface can be polished with the composite oxideparticles.

When an uneven surface is polished as an example of the surface to bepolished, the polishing progress can be assumed microscopically asfollows. During the early stage, a larger polishing load than the setload of the polishing apparatus is applied to the convex portions, sothat the coating is broken and the convex portions are increasinglypolished. On the other hand, since a lower polishing load is applied tothe concave portions, the concave portions are protected by the coatingand not likely to be polished. In other words, the convex portions areselectively polished to reduce the difference in level between theconvex and concave portions, and thus planarization proceeds.

As described above, the use of the polishing liquid composition of thisembodiment, combined with the effect of the composite oxide particlescapable of high speed polishing, can provide a polished surface withexcellent flatness in a short time. However, the present invention isnot limited to these assumptions.

If the set load of the polishing apparatus is set so that a flat surfaceis not substantially polished, then the polishing hardly proceeds afterthe difference in level between the convex and concave portions iseliminated. This is preferred because excessive polishing can be easilyprevented.

The water-soluble organic compound may have at least one selected from—SO₃H group, —SO₃N_(a) group (N_(a) is an atom or atomic group that cansubstitute for the H atom to form a salt), —COOH group, and —COON_(b)group (N_(b) is an atom or atomic group that can substitute for the Hatom to form a salt). When the water-soluble organic compound is a salt,it is preferably a non-metallic salt that does not contain an alkalimetal. The polishing liquid composition may include one or more types ofwater-soluble organic compounds.

The water-soluble organic compound may be, e.g., at least one selectedfrom the group consisting of a water-soluble acrylic acid-based polymer,organic acid and its salt, acidic amino acid and its salt, neutral orbasic amino acid, and an amphoteric water-soluble low-molecular weightorganic compound (also referred to simply as a low-molecular weightorganic compound in the following). From the viewpoint of ensuring thestability of the polishing liquid composition, the molecular weight ofthe low-molecular weight organic compound is preferably 1000 or less,more preferably 500 or less, and even more preferably 300 or less.

As an example of the water-soluble organic compound, the water-solubleacrylic acid-based polymer included in the polishing liquid compositionof this embodiment may be, e.g., polyacrylic acid or acrylic acid-basedcopolymer. The polyacrylic acid includes a polymer having aconstitutional unit (A) derived from at least one monomer (a) selectedfrom the group consisting of acrylic acid and a non-metallic salt ofacrylic acid. The water-soluble acrylic acid-based polymer may be, e.g.,a copolymer having the constitutional unit (A) and a constitutional unit(B) derived from the following monomer (b).

The non-metallic salt of acrylic acid may be, e.g., an acrylic acidammonium salt, an acrylic acid amine salt, or an acrylicacid-tetraalkylammonium salt. The water-soluble acrylic acid-basedpolymer may include one or more constitutional units derived from theseacrylates.

The constitutional unit (A) of the acrylic acid-based copolymer is morethan 50 mol % of the total constitutional unit, but preferably more than70 mol %, more preferably more than 80 mol %, and even more preferablymore than 90 mol %.

The monomer (b) contains a polymerizable double bond. Examples of themonomer (b) include the following: carboxylic acid-based monomers suchas itaconic acid, methacrylic acid, maleic acid, fumaric acid,citraconic acid, glutaconic acid, vinylacetic add, allylacetic acid,phosphinocarboxylic acid, α-haloacrylic acid, and β-carboxylic acid orsalts of these acids; sulfonic acid-based monomers such as2-acrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid,vinylsufonic acid, allylsulfonic acid, and methallylsulfonic acid orsalts of these acids; phosphoric acid-based monomers such as acidphosphooxyethyl(meth)acrylate, acid phosphooxypropyl(meth)acrylate, and3-(meth)acryloyl oxypropyl phosphonate or salts of these acids:(meth)acrylate alkyl ester-based monomers such as methyl(meth)acrylate,ethyl(meth)acrylate, octyl(meth)acrylate), 2-hydroxyethyl(meth)acrylate,polyethylene glycol(meth)acrylate, and methoxypolyethyleneglycol(meth)acrylate; N-alkyl substituted (meth)acrylamide-basedmonomers such as N, N-dimethyl(meth)acrylamide andN,N-diethyl(meth)acrylamide; aromatic vinyl-based monomers such asstyrene; α-olefin-based monomers such as isobutylene and diisobutylene;vinyl ether-based monomers such as vinyl methyl ether and vinyl ethylether; nitrile-based monomers such as (meth)acrylonitrile; and vinylester-based monomers such as vinyl acetate and vinyl propionate.

The water-soluble acrylic acid-based polymer may be in the form ofeither free acid or salt. Generally the water-soluble acrylic acid-basedpolymer is used in the form of free acid or salt to produce thepolishing liquid composition. However, the salt is preferred for theproduction of the polishing liquid composition because of its highsolubility in the aqueous medium.

The salt of the water-soluble acrylic acid-based polymer can be producedin such a manner that an acid typo acrylic acid monomer is polymerizedalone or copolymerized with the monomer (b), and then is neutralisedwith a predetermined alkali at a predetermined rate. The preferredexamples of the salt include an ammonium compound salt, a lithium salt,a sodium salt, a potassium salt, and a cesium salt. From the viewpointof achieving the favorable electric characteristics of LSI, the ammoniumcompound salt is more preferred.

The preferred examples of amines constituting the ammonium compound saltinclude ammonia, primary, secondary, and tertiary amines having astraight or branched chain saturated or unsaturated alkyl group with acarbon number of 1 to 10, primary, secondary, and tertiary amines havingat least one aromatic ring with a carbon number of 6 to 10, amine havinga cyclic structure such as piperidine or piperazine, and atetraalkylammonium compound such as tetramethylammonium.

From the viewpoint of the solubility in the aqueous medium and thedispersion stability, it is preferable that the salt of thewater-soluble acrylic acid-based polymer is neutralized at apredetermined rate in accordance with the type of the water-solubleacrylic acid-based polymer.

From the viewpoint of suppressing a dishing phenomenon due to excessivepolishing and providing a polished surface with excellent flatness, thefollowing water-soluble acrylic acid-based polymers are preferred. Thedishing phenomenon indicates that while the uneven surface is polished,the concave portions are excessively polished, and thus the portions ofthe polished surface that particularly correspond to those concaveportions are recessed like a dish. Such a dishing phenomenon occurs moreconspicuously as a distance between the adjacent convex portionsincreases, that is, the proportion of the entire area of the concaveportions shown in a plan view of the uneven surface becomes larger(i.e., the surface density of the concave portion becomes larger).

The preferred examples of the water-soluble acrylic acid-based polymerinclude polyacrylic acid, polymethacrylic acid, ammonium polyacrylate,ammonium polymethacrylate, a polyacrylic acid ammonium salt, an ammoniumsalt of a copolymer of acrylic acid and maleic acid, an ammonium salt ofa copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonicacid, and an ammonium salt of a copolymer of acrylic acid andmethyl(methyl)acrylate. In particular, the polyacrylic acid ammoniumsalt is more preferred.

From the viewpoint of suppressing a dishing phenomenon due to excessivepolishing, providing a polished surface with excellent flatness, andachieving the dispersion stability of the abrasive grains, the weightaverage molecular weight of the water-soluble acrylic acid-based polymeris preferably 300 to 100000, more preferably 500 to 50000, even morepreferably 1000 to 30000, and much more preferably 2000 to 10000. It ispreferable that the weight average molecular weight of the salt of thewater-soluble acrylic acid-based polymer also falls in the above rangesfor the same reason. When the water-soluble acrylic acid-based polymeris ammonium polyacrylate, the weight average molecular weight ispreferably 1000 to 20000, and more preferably 2000 to 10000.

When the polishing liquid composition includes ammonium polyacrylate asthe water-soluble acrylic acid-based polymer, from the viewpoint ofproviding a polished surface with more excellent flatness, the contentof the ammonium polyacrylate in the polishing liquid composition ispreferably 0.1 to 15 wt %, more preferably 0.2 to 10 wt %, even morepreferably 0.5 to 8 wt %, and much more preferably 1.0 to 6 wt %.

From the viewpoint of effectively suppressing the occurrence of dishing,the weight ratio of the ammonium polyacrylate to the composite oxideparticles (ammonium polyacrylate/composite oxide particles) in thepolishing liquid composition of this embodiment is preferably 1/5 ormore, more preferably 1/4 or more, and even more preferably 1/3 or more.From the viewpoint of further improving the polishing rate, the weightratio (ammonium polyacrylate/composite oxide particles) is preferably15/1 or less, more preferably 12/1 or less, and even more preferably10/1 or less. Accordingly, the weight ratio is preferably 1/5 to 15/1,more preferably 1/4 to 12/1, and even more preferably 1/3 to 10/1.

As an example of the water-soluble organic compound, the preferredexamples of the organic acid and its salt included in the polishingliquid composition of this embodiment include malic acid, lactic acid,tartaric acid, gluconic acid, citric acid hydrate, succinic acid, adipicacid, fumaric acid, and ammonium salts of these acids.

As an example of the water-soluble organic compound, the preferredexamples of the acidic amino acid and its salt included in the polishingliquid composition of this embodiment include aspartic acid, glutamicacid, and ammonium salts of these acids.

As an example of the water-soluble organic compound, the preferredexamples of the neutral or basic amino acid included in the polishingliquid composition of this embodiment include glycine, 4-aminobutyricacid, 6-aminohexanoic acid, 12-aminolauric acid, arginine, andglycylglycine.

As an example of the water-soluble compound, the preferred examples ofthe low-molecular weight organic compound included in the polishingliquid composition of this embodiment include dihydroxyethylglycine(DHEG), ethylenediaminetetraacetic acid (EDTA),cyclohexanediaminetriacetic acid (CyDTA), nitrilotriacetic acid (NTA),hydroxyethylethylenediaminetriacetic acid (HEDTA),diethylenetriaminepentaacetic acid (DTPA),triethylenetetraminehexaacetic acid (TTHA), L-glutamic acid diaceticacid (GLDA), amino(methylenephosphonic acid),1-hydroxyethylidene1,1-diphosphonic acid (HEDP),ethylene-diaminetetra(methylenephosphonic acid),diethylenetriaminepenta(methylenephosphonic acid), β-alaninediaceticacid (β-ADA), α-alaninediacetic acid (α-ADA), aspartic acid diaceticacid (ASDA), ethylenediaminedisuccinic acid (EDDS), iminodiacetic acid(IDA), hydroxyethyliminodiacetic acid (HEIDA),1,3-propanediaminetetraacetic acid (1,3-PDTA), aspartic acid, serine,cysteine, azaserine, asparagine, 2-aminobutyric acid, 4-aminobutyricacid, alanine, β-alanine, arginine, alloisoleucine, allothreonine,isoleucine, ethionine, ergothioneine, ornithine, canavanine,S-(carboxymethyl)-cysteine, kynurenine, glycine, glutamine, glutamicacid, creatine, sarcosine, crystathionine, cystine, cysteic acid,citrulline, β-(3,4-dihydroxyphenyl)-alanine, 3,5-diiodotyrosine,taurine, thyroxine, tyrosine, tryptophan, threonine, norvaline,norleucine, valine, histidine, 4-hydroxyproline, δ-hydroxylysine,phenylalanine, proline, homoserine, methionine, 1-methylhistidine,3-methylhistidine, lanthionine, lysine, leucine, m-aminobenzoic acid,p-aminobenzoic acid, β-aminoisovaleric acid, 3-aminocrotonic acid,o-aminocinnamic acid, m-aminobenzenesulfonic acid,p-aminobenzenesulfonic acid, 2-aminopentanoic acid, 4-aminopentanoicacid, 5-aminopentanoic acid, 2-amino-2-methylbutyric acid,3-aminobutyric acid, isatic acid, 2-quinolinecarboxylic acid,3-quinolinecarboxylic acid, 4-quinolinecarboxylic acid,5-quinolinecarboxylic acid, 2,3-quinolinedicarboxylic acid,2,4-quinoline-dicarboxylic acid, guanidinoacetic acid,2,3-diaminobenzoic acid, 2,4-diaminobenzoic acid, 2,5-diaminobenzoicacid, 3,4-diaminophenol, 2,4,6-triaminophenol, 2-pyridinecarboxylicacid, nicotinic acid, isonicotinic acid, 2,3-pyridine-dicarboxylic acid,2,4-pyridinedicarboxylic acid, 2,5-pyridinedicarboxylic acid,2,6-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid,3,5-pyridinedicarboxylic acid, 2,4,5-pyridinecarboxylic acid,N-phenylglycerine-o-carboxylic acid, phenol-2,4-disulfonic acid,o-phenolsulfonic acid, m-phenolsulfonic acid, p-phenolsulfonic acid,phthalanilic acid, o-(methylamino)phenol, m-(methylamino)phenol,p-(methylamino)phenol, carboxybetaine, sulfobetaine, imidazoliniumbetaine, and lecithin. The preferred examples of the low-molecularweight organic compound also include dielectric substances obtained bysubstituting atoms such as F, Cl, Br, and I or atomic groups such as OH,CN, and NO₂ for one or more protons of these compounds. In particular,from the viewpoint of suppressing a dishing phenomenon due to excessivepolishing and providing a polished surface with excellent flatness, thefollowing chelating agents are more preferred.

The chelating agents include DHEG, EDTA, CyDTA, NTA, HEDTA, DTPA, TTHA,GLDA, aminotri(methylenephosphnic acid), HEDP,ethylenediaminetetra(methylenephosphonic acid),diethylenetriaminepenta(methylenephosphonic acid), β-ADA, α-ADA, ASDA,EDDS, IDA, HEIDA, 1,3-PDTA, aspartic acid, serine, and cysteine. Amongthem, DHEG, EDTA, NTA, β-ADA, α-ADA, ASDA, EDDS, HEIDA, aspartic acid,serine, and cysteine are more preferred.

From the viewpoint of ensuring the stability of the polishing liquidcomposition when it is concentrated, DHEG is even more preferred in thechelating agents.

In the above amphoteric water-soluble low-molecular weight organiccompounds, particularly DHEG, in which an anionic group, a cationicgroup, and a nonionic group are present in balance in the molecules,does not significantly reduce the zeta potential or hydrophilicity ofthe composite oxide particles even if DHEG adsorbs to the compositeoxide particles, and DHEG also is considered to have little influence onthe effect of a dispersing agent. Moreover, DHEG can suppress theaggregation or the like of the composite oxide particles sufficiently,and therefore can ensure the dispersion stability of the composite oxideparticles even if the concentration of the composite oxide particles ishigh. Thus, the polishing liquid composition of this embodiment thatincludes DHEG may be provided as a high-concentration polishing liquidcomposition with stable quality.

Generally, the low-molecular weight organic compound is used in the formof free acid or salt to produce the polishing liquid composition.However, the salt is preferred for the production of the polishingliquid composition because of its high solubility in the aqueous medium.

The preferred examples of the salt include an ammonium compound salt, alithium salt, a sodium salt, a potassium salt, and a cesium salt. Fromthe viewpoint of achieving the favorable electric characteristics ofLSI, the ammonium compound salt is more preferred.

The preferred examples of amines constituting the ammonium compound saltinclude ammonia, primary, secondary, and tertiary amines having astraight or branched chain saturated or unsaturated alkyl group with acarbon number of 1 to 10, primary, secondary, and tertiary amines havingat least one aromatic ring with a carbon number of 6 to 10, amine havinga cyclic structure such as piperidine or piperazine, and atetraalkylammonium compound such as tetramethylammonium.

From the viewpoint of providing a polished surface with excellentflatness, the content of the water-soluble organic compound in thepolishing liquid composition of this embodiment is preferably 0.02 to 15wt %, more preferably 0.05 to 10 wt %, even more preferably 0.1 to 8 wt%, and much more preferably 0.2 to 6 wt %.

In the polishing liquid composition of the present invention, thesubstance added as the water-soluble organic compound may be either thesame as or different from the substance added as a dispersing agent,which will be described later. When the substance added as thewater-soluble organic compound is the same as that added as thedispersing agent may be selected from the range of the sum of preferredcontents of the water-soluble organic compound (e.g., 0.02 to 15 wt %)and the dispersing agent (e.g., 0.0005 to 0.5 wt %) so as to achievegood dispersibility and good flatness of the polished surface.

From the viewpoint of providing a polished surface with a high flatness,the weight ratio of the water-soluble organic compound to the compositeoxide particles (water-soluble organic compound/composite oxideparticles) in the polishing liquid composition of this embodiment ispreferably 1/30 or more, more preferably 1/20 or more, and even morepreferably 1/10 or more. From the viewpoint of further improving thepolishing rate, the weight ration is preferably 15/1 or less, morepreferably 12/1 or less, and even more preferably 10/1 or less.Accordingly, the weight ratio is preferably 1/30 to 15/1, morepreferably 1/20 to 12/1, and even more preferably 1/10 to 10/1.

When the polishing liquid composition includes DHEG as the water-solubleorganic compound, from the viewpoint of providing a polished surfacewith more excellent flatness, the content of DHEG in the polishingliquid composition is preferably 0.1 to 15 wt %, more preferably 0.2 to10 wt %, even more preferably 0.5 to 8 wt %, and much more preferably1.0 to 6 wt %.

From the viewpoint of effectively suppressing the occurrence of dishing,the weight ratio of DHEG to the composite oxide particles(DHEG/composite oxide particles) in the polishing liquid composition ofthis embodiment is preferably 1/5 or more, more preferably 1/4 or more,and even more preferably 1/3 or more. From the viewpoint of furtherimproving the polishing rate, the weight ratio (DHEG/composite oxideparticles) is preferably 15/1 or less, more preferably 12/1 or less, andeven more preferably 10/1 or less. Accordingly, the weight ratio ispreferably 1/5 to 15/1, more preferably 1/4 to 12/1, and even morepreferably 1/3 to 10/1.

The aqueous medium included in the polishing liquid composition of thisembodiment may be the same as that included in the polishing liquidcomposition of Embodiment 1.

The type, content, weight average molecular weight, etc. of thedispersing agent included in the polishing liquid composition of thisembodiment may be the same as those of the dispersing agent included inthe polishing liquid composition of Embodiment 1.

The polishing liquid composition of this embodiment further may includeat least one type of optional component selected from a pH adjuster, anantiseptic agent, and an oxidizing agent as long as the optionalcomponent does not interfere with the effect of the present invention.The specific examples of these optional components may be the same asthose described in Embodiment 1. The preferred pH of the polishingliquid composition at 25° C. may be the same as that of the polishingliquid composition of Embodiment 1.

Although the above content of each component is applied to the polishingliquid composition in use, the polishing liquid composition of thisembodiment may be preserved and provided in the form of a concentrate aslong as its stability is not impaired. This is preferred because theproduction and transportation costs can be reduced further. Theconcentrate may be diluted appropriately with the above aqueous mediumas needed.

When the polishing liquid composition of this embodiment is in the formof a concentrate, from the viewpoint of further reducing the productionand transportation costs, the content of the composite oxide particlesis preferably 1 wt % or more, more preferably 2 wt % or more, even morepreferably 3 wt % or more, and much more preferably 4 wt % or more. Fromthe viewpoint of further improving the dispersion stability, the contentof the composite oxide particles is preferably 20 wt % or less, morepreferably 15 wt % or less, even more preferably 10 wt % or less, andmuch more preferably 8 wt % or less. According, the content of thecomposite oxide particles in the concentrate is preferably 1 to 20 wt %,more preferably 2 to 15 wt %, even more preferably 3 to 10 wt %, andmuch more preferably 4 to 8 wt %.

When the polishing liquid composition of this embodiment is in the formor a concentrate, from the viewpoint of further reducing the productionand transportation costs, the content of the water-soluble organiccompound is preferably 0.08 wt % or more, more preferably 0.2 wt % ormore, even more preferably 0.5 wt % or more, and much more preferably 1wt % or more. From the viewpoint of further improving the dispersionstability, the content of the water soluble organic compound in theconcentrate is preferably 40 wt % or less, more preferably 20 wt % orless, even more preferably 15 wt % or less, and much more preferably 12wt % or less. Accordingly, the content of the water-soluble organiccompound in the concentrate is preferably 0.08 to 40 wt %, morepreferably 0.2 to 20 wt %, even more preferably 0.5 to 15 wt %, and muchmore preferably 1 to 12 wt %.

When the polishing liquid composition including DHEG as thelow-molecular weight organic compound is in the form of a concentration,from the viewpoint of further reducing the production and transportationcosts, the content of DHEG is preferably 0.4 wt % or more, morepreferably 1 wt % or more, even more preferably 2 wt % or more, and muchmore preferably 3 wt % or more. From the viewpoint of further improvingthe dispersion stability, the content of DHEG in the concentrate ispreferably 40 wt % or less, more preferably 20 wt % or less, even morepreferably 15 wt % or less, and much more preferably 12 wt % or less.Accordingly, the content of DHEG in the concentrate is preferably 0.4 to40 wt %, more preferably 1 to 20 wt %, even more preferably 2 to 15 wt%, and much more preferably 3 to 12 wt %.

When the polishing liquid composition of this embodiment is in the formof a concentrate, from the viewpoint of further reducing the productionand transportation costs, the content of the dispersing agent ispreferably 0.001 wt % or more, more preferably 0.003 wt % or more, evenmore preferably 0.005 wt % or more, and much more preferably 0.01 wt %or more. From the viewpoint of further improving the dispersionstability, the content of the dispersing agent in the concentrate ispreferably 1.0 wt % or less, more preferably 0.3 wt % or less, even morepreferably 0.2 wt % or less, and much more preferably 0.1 wt % or less.Accordingly, the content of the dispersing agent in the concentrate ispreferably 0.001 to 1.0 wt %, more preferably 0.003 to 0.3 wt %, evenmore preferably 0.005 to 0.2 wt %, and much more preferably 0.01 to 0.1wt %.

Next, an example of a method for manufacturing the polishing liquidcomposition of this embodiment will be described.

The method for producing the polishing liquid composition of thisembodiment is not limited at all. For example, the polishing liquidcomposition may be produced by mixing the composite oxide particles, thedispersing agent, the water-soluble organic compound (DHEG, ammoniumpolyacrylate, etc.), the aqueous medium, and the optional component asneeded.

The mixing order of these components is not particularly limited, andall the components may be mixed simultaneously. Alternatively, acomposite oxide particle slurry may be prepared beforehand by dispersingthe composite oxide particles in the aqueous medium in which thedispersing agent is dissolved, and then this slurry may be blended witha mixture including the water-soluble organic compound and the remainingaqueous medium. From the viewpoint of sufficiently preventing theaggregation or the like of the composite oxide particles, the latter ispreferred.

The composite oxide particles can be dispersed in the aqueous medium,e.g., using an agitator such as a homomixer, a homogenizer, anultrasonic disperser, a wet ball mill, or a bead mill. If coarseparticles resulting from the aggregation or the like of the compositeoxide particles are present in the aqueous medium, it is preferable thatthe coarse particles should be removed by centrifugal separation orfiltration. The composite oxide particles are dispersed preferably inthe presence of the dispersing agent.

Next, a method for manufacturing a semiconductor device of thisembodiment will be described.

A method for manufacturing a semiconductor substrate of this embodimentincludes the following: a thin film formation process of forming a thinfilm on one principal surface side of the semiconductor substrate; anuneven surface formation process of forming a concavo-convex on thesurface of the thin film that is opposite to the surface facing thesemiconductor substrate; and a polishing process of polishing the unevensurface with the polishing liquid composition of this embodiment. Thethin film formation process is performed multiple times as needed.

Another method for manufacturing a semiconductor substrate of thisembodiment includes the following: a thin film formation process offorming a thin film with an uneven surface on one principal surface sideof the semiconductor substrate; and a polishing process of polishing theuneven surface with the polishing liquid composition of this embodiment.The thin film formation process is performed multiple times as needed.

The thin film formed by the thin film formation process may be, e.g., aninsulating layer or a conductor layer such as a metal layer or asemiconductor layer. The material of the insulating layer may be, e.g.,silicon oxide, silicon nitride, or polysilicon.

A method for forming the thin film may be selected appropriately inaccordance with the material constituting the thin film. For example, aCVD method, a PVD method, a coating method, and a plating method can beused.

The uneven surface may be formed by a conventionally known lithographytechnique or the like. In the lithography technique, photoresistcoating, exposure, development, etching, removal of the photoresist,etc. are performed in this order. In some cases, the uneven surface maybe formed so as to correspond to a concavo-convex pattern of the lowerlayer.

The uneven surface can be polished by supplying the polishing liquidcomposition of this embodiment to the uneven surface and/or the surfaceof a polishing pad, bringing, e.g., the polishing pad into contact withthe uneven surface, and moving at least one of the thin film having theuneven surface and the polishing pad relative to the other whileapplying a predetermined pressure (load) to the uneven surface. Thepolishing treatment can be performed by a conventionally known polishingapparatus.

The polishing liquid composition may be used as it is or diluted if itis in the form of a concentrate. When the concentrate is diluted, thedilution factor is not particularly limited and may be determinedappropriately in accordance with the concentration of each component inthe concentrate, the polishing conditions, or the like.

Specifically, the dilution factor is preferably 1.5 times or more, morepreferably 2 times or more, even more preferably 3 times or more, andmuch more preferably 4 times or more. The dilution factor is preferably20 times or less, more preferably 15 times or less, even more preferably10 times or less, and much more preferably 8 times or less. Accordingly,the dilution factor is preferably 1.5 to 20 times, more preferably 2 to15 times, even more preferably 3 to 10 times, and much more preferably 4to 8 times.

Examples of the material of the semiconductor substrate include anelementary semiconductor such as Si or Ge, a compound semiconductor suchas GaAs, InP, or CdS, and a mixed crystal semiconductor such as InGaAsor HgCdTe.

Examples of the material of the thin film for which the polishing liquidcomposition of this embodiment is used more suitably include thefollowing materials that are conventionally known as constituting asemiconductor device: a metal such as aluminum, nickel, tungsten,copper, tantalum, or titanium; a semimetal such as silicon; an alloycontaining any of these metals as the main component; a glass materialsuch as glass, glassy carbon, or amorphous carbon; a ceramic materialsuch as alumina, silicon dioxide, silicon nitride, tantalum nitride, ortitanium nitride; and a resin, such as a polyimide resin. In particular,the thin film preferably includes silicon, more preferably includes atleast one selected from the group consisting of silicon oxide, siliconnitride, and polysilicon, and even more preferably includes siliconoxide, since such a thin film can be polished favorably with thepolishing liquid composition of this embodiment. The silicon oxide maybe, e.g., quartz, glass, silicon dioxide, or tetraethoxysilane (TEOS).The thin film including the silicon oxide may be doped with elementssuch as phosphorus and boron. Specific examples of such a thin filminclude a BPSG (boro-phospho-silicate glass) film and a PSG(phospho-silicate glass) film. The silicon oxide film doped with theseelements is polished more easily than the silicon oxide film that is notdoped with the elements. Therefore, the polishing liquid compositionneeds to include a larger amount of the water-soluble organic compoundto facilitate the penalization. However, when the polishing liquidcomposition includes the water-soluble organic compound in quantity, thecomposite oxide particles can be aggregated and settled out. In anexample of the polishing liquid composition of this embodiment thatincludes DHEG as the water-soluble organic compound, even if the contentof DHEG is, e.g., 0.2 to 20 wt %, the aggregation of the composite oxideparticles is suppressed sufficiently, and the dispersion stability isextremely high. Thus, an example of the polishing liquid composition ofthis embodiment is particularly suitable for the polishing of the BPSGfilm, the PSG film, or the like.

From the viewpoint of quickly polishing the convex portions and enablingthe formation of a polished surface with higher flatness, the method formanufacturing a semiconductor device of this embodiment is useful in thecase where the entire uneven surface is composed of the same material.

A difference in level (H) between the mutually adjacent convex andconcave portions (see, e.g., FIG. 4A) is preferably 50 to 2000 nm, andmore preferably 100 to 1500 nm. The “difference in level (H)” means adistance between the top of the convex portion and the bottom of theconcave portion, and can be determined with a profile measuringapparatus (HRP-100 manufactured by KLA-Tencor Corporation).

The material or the like of the polishing pad used in the polishingprocess is not particularly limited, and any conventionally knownmaterials can be used. Examples of the material of the polishing padinclude an organic polymer foam such as a nonwoven fabric or a rigidpolyurethane foam and an inorganic foam. In particular, the rigidpolyurethane foam is preferred.

From the viewpoint of further improving the polishing rate, the supplyrate of the polishing liquid composition is preferably 0.01 g/min ormore, more preferably 0.05 g/min or more, and even, more preferably 0.1g/min or more per 1 cm² of the surface to be polished. From theviewpoint of reducing the cost and facilitating the disposal of liquidwastes, the supply rate of the polishing liquid composition ispreferably 10 g/min or less, more preferably 5 g/min or less, and evenmore preferably 3 g/min or less per 1 cm² of the uneven surface.Accordingly, the supply rate of the polishing liquid composition ispreferably 0.01 to 10 g/min, more preferably 0.05 to 5 g/min, and evenmore preferably 0.1 to 3 g/min per 1 cm² of the surface to be polished.

The polishing liquid composition of this embodiment is not limited to asingle-liquid type that is put on the market with all the componentsbeing mixed beforehand, but can be a two-liquid type including separatecomponents that are to be mixed at the time of use. In the two-liquidtype polishing liquid composition, the aqueous medium is divided into afirst aqueous medium and a second aqueous medium, and the polishingliquid composition is composed of an aqueous medium composition (I)including the composite oxide particles, the dispersing agent, and thefirst aqueous medium and an aqueous medium composition (II) includingthe water-soluble organic compound and the second aqueous medium. Theaqueous medium composition (I) also may include part of thewater-soluble organic compound other than the composite oxide particlesand the dispersing agent. The aqueous medium composition (II) also mayinclude part of the composite oxide particles and part of the dispersingagent other than the water-soluble organic compound. When thewater-soluble organic compound is a water-soluble acrylic acid-basedpolymer from the viewpoint of facilitating the mixing of the componentsat the time of use, it is preferable that the aqueous medium composition(I) does not include the water-soluble acrylic acid-based polymer andthe aqueous medium composition (II) does not include the composite oxideparticles.

The aqueous medium compositions (I) and (II) may be either mixed beforethey are supplied to the uneven surface or mixed on the uneven surfaceafter they have been supplied separately. The aqueous medium composition(II) (i.e., additive aqueous solution) that includes the water-solubleorganic compound and the second aqueous medium and is used with theaqueous medium composition (I) can act as a planarization acceleratorduring polishing.

Next, the content or the like of each component of an example of thetwo-liquid type polishing liquid composition will be described. In thisexample, however, the aqueous medium composition (I) does not includethe water-soluble organic compound and the aqueous medium composition(II) does not include the composite oxide particles and the dispersingagent.

The content of each component in the two-liquid type polishing liquidcomposition may be the same as that of each component in a single-liquidtype polishing liquid composition when the aqueous medium compositions(I) and (II) are mixed. For example, the content of the composite oxideparticles in the aqueous medium composition (I), the content of thedispersing agent in the aqueous medium composition (I), and the contentof the water-soluble organic compound in the aqueous medium composition(II) can be preferably as follows.

From the viewpoint of further improving the polishing rate, the contentof the composite oxide particles in the aqueous medium composition (I)is preferably 0.1 wt % or more, more preferably 0.2 wt % or more, evenmore preferably 0.4 wt % or more, and much more preferably 0.5 wt % ormore. From the viewpoint of further improving the dispersion stabilityand reducing the cost, the content of the composite oxide particles inthe aqueous medium composition (I) is preferably 8 wt % or less, morepreferably 5 wt % or less, even more preferably 4 wt % or less, and muchmore preferably 3 wt % or less. Accordingly, the content of thecomposite oxide particles is preferably 0.1 to 8 wt %, more preferably0.2 to 5 wt %, even more preferably 0.4 to 4 wt %, and much morepreferably 0.5 to 3 wt %.

From the viewpoint of further improving the dispersion stability, thecontent of the dispersing agent in the aqueous medium composition (I) ispreferably 0.0005 wt % or more, more preferably 0.001 wt % or more, andeven more preferably 0.002 wt % or more. Moreover, the content of thedispersing agent in the aqueous medium composition (I) is preferably 0.5wt % or less, more preferably 0.1 wt % or less, and even more preferably0.05 wt % or less. Accordingly, the content of the dispersing agent ispreferably 0.0005 to 0.5 wt %, more preferably 0.001 to 0.1 wt %, andeven more preferably 0.002 to 0.05 wt %.

From the viewpoint of providing a polished surface with excellentflatness, the content of the water-soluble organic compound in theaqueous medium composition (II) (i.e., additive aqueous solution) ispreferably 0.04 to 60 wt %, more preferably 0.1 to 50 wt %, even morepreferably 0.2 to 40 wt %, and much more preferably 0.4 to 30 wt %.

From the viewpoint of improving the liquid supply accuracy and providinga uniform mixed solution, the mixing ration of the aqueous mediumcomposition (I) to the aqueous medium composition (II) (i.e., additiveaqueous solution) (weight of aqueous medium composition (I)/weight ofaqueous medium composition (II) is preferably 1/2 to 50/1, morepreferably 2/1 to 40/1, even more preferably 5/1 to 30/1, and much morepreferably 10/1 to 20/1.

From the viewpoint of further improving the dispersion stability, the pHof the aqueous medium composition (I) at 25° C. is preferably 2 to 11,more preferably 3 to 10, even more preferably 4 to 10, and much morepreferably 5 to 9.

The preferred pH of the aqueous medium composition (II) at 25° C. variesdepending on the type of the water-soluble organic compound and may bedetermined so that the pH of the polishing liquid composition obtainedby mixing the aqueous medium compositions (I) and (II) falls in thepreferred pH range as described above. For example, when thewater-soluble organic compound is DHEG or ammonium polyacrylate, fromthe viewpoint of further improving the dispersion stability of thecomposite oxide particles, the pH of the aqueous medium composition (II)at 25° C. is preferably 3 to 10, more preferably 3 to 8, even morepreferably 4 to 7, and much more preferably 4 to 6.

Whether the polishing liquid composition is a single-liquid type or atwo-liquid type, from the viewpoint of suppressing the adverse effect onthe planarization and the occurrence of scratches caused by an excessiveload, the set polishing load of the polishing apparatus provided withthe polishing pad is preferably 100 kPa or less, more preferably 70 kPaor less, and even more preferably 50 kPa or less. From the viewpoint ofshortening the polishing time, the set polishing load is preferably 5kPa or more, and more preferably 10 kPa or more. Accordingly, the setpolishing load is preferably 5 to 100 kPa, more preferably 10 to 70 kPa,and even more preferably 10 to 50 kPa.

When the polishing pad is a rotating pad, the number of revolutions ofthe polishing pad is preferably 30 to 200 rpm, more preferably 45 to 150rpm, and even more preferably 60 to 100 rpm. The number of revolutionsof the object to be polished is preferably 30 to 200 rpm, morepreferably 45 to 150 rpm, and even more preferably 60 to 100 rpm.

The above polishing process can be applied to any type of polishingduring the manufacturing process of the semiconductor device. Specificexamples include (1) polishing performed in the process of forming aburied isolation film, (2) polishing performed in the process offlattening an interlayer insulating film, (3) polishing performed in theprocess of forming buried metal wiring (damascene interconnect etc.),and (4) polishing performed in the process of forming a buriedcapacitor. In particular, the polishing process in the manufacturingmethod of the semiconductor device of this embodiment is preferablyapplied to (1) and (2).

The manufacturing method of the semiconductor device of this embodimentmay include a cleaning process, a heat-treatment process, an impuritydiffusion process, or the like as needed.

Examples of the semiconductor device include a memory IC (integratedcircuit), a logic IC, and system LSI (large-scale integration).

The polishing liquid composition of this embodiment is used, e.g., topolish the oxide film 3 in the process of forming a buried isolationfilm during the manufacturing process of the semiconductor device, asdescribed with reference to FIGS. 1A to 1D in Embodiment 1. Moreover,the polishing liquid composition of this embodiment is used, e.g., topolish the oxide film 21 in the process of flattening an interlayerinsulating film during the manufacturing process of the semiconductordevice, as described with reference to FIGS. 2A to 3B in Embodiment 1.

As described above, this embodiment can provide a polishing liquidcomposition capable of forming a polished surface with high flatness bypolishing in a short time, a polishing method using this polishingliquid composition, and a method for manufacturing a semiconductordevice.

EXAMPLES

<Object to be Polished>

1. Base Material of Aluminosilicate Glass Substrate Used for Hard Disk

A base material of an aluminosilicate glass substrate (referred to as a“glass base material” in the following) used for a hard disk wasprepared. This glass base material was polished beforehand with apolishing liquid composition including ceria particles as a polishingagent. The surface roughness of the glass base material was 0.3 nm(AFM-Ra), the thickness was 0.635 mm, the outer diameter was 65 mm, andthe inner diameter was 20 mm.

2. Synthetic Quartz Wafer

A synthetic quartz wafer (manufactured by Optostar Ltd.) having twolapped principal surfaces, a diameter of 5.08 cm (2 inches), and athickness of 1.0 mm was prepared.

3. Silicon Wafer Provided with TEOS (Tetraethoxysilane) Film

A 2000 nm thick TEOS film was formed on a silicon wafer with a diameterof 20.32 cm (8 inches) by a parallel-plate plasma chemical vapordeposition (p-CVD) method.

4. Silicon Wafer Provided with Thermal Oxide Film

A 2000 nm thick silicon dioxide film was formed on a silicon wafer witha diameter of 20.82 cm (8 inches). The silicon dioxide film was obtainedby exposing the silicon wafer to an oxygen gas or steam in an oxidationfurnace so that silicon in the silicon water was allowed to react withoxygen.

5. Silicon Wafer Provided with HDP Film

A 1000 nm thick silicon oxide film was formed on a silicon wafer with adiameter of 20.32 cm (8 inches) by a high-density plasma chemical vapordeposition (HDP-CVD) method.

<Polishing Conditions>

1. Polishing of Glass Base Material or Synthetic Quartz Wafer

Polishing test machine: a single-sided polishing machine MA-300 with aplaten diameter of 300 mm manufactured by Musashino Electronic Co., Ltd.

Polishing pad: a laminated pad of IC1000 (hard urethane pad) and suba400(nonwoven fabric pad) manufactured by NITTA HAAS INCORPORATED or NP025(suede-type pad) manufactured by FILWEL CO., LTD.

Number of revolutions of platen: 90 r/min

Number of revolutions of carrier: 90 r/min (a forced drive system)

Supply rate of polishing liquid composition: 50 g/min (about 1.5mL/min/cm²)

Polishing time: 15 min

Polishing load: 300 g/cm² (a constant load applied by a weight)

Dress conditions: A brush was dressed by supplying ion-exchanged waterto the brush for 1 minute before polishing.

2. Polishing of TEOS Film, Thermal Oxide Film, or HDP Film

Polishing test machine: a single-sided polishing machine LP-541 with aplaten diameter of 540 mm manufactured by Lapmaster SFT Corp.

Polishing pad: a laminated pad of IC1000 (hard urethane pad) and suba400(nonwoven fabric pad) manufactured by NITTA HAAS INCORPORATED

Number of revolutions of platen: 100 rpm

Number of revolutions of bead: 110 rpm (the rotation direction is thesame as that of the platen)

Polishing time: 1 min

Polishing load: 30 kPa (a set value)

Supply of polishing liquid composition: 200 ml/min

<Evaluation Method>

Using the polishing liquid compositions of Examples 1 to 20 andComparative Examples 1 to 14 (see Tables 1 to 3), the objects to bepolished were polished, and then cleaned with running ion-exchangedwater. Subsequently, the objects to be polished were immersed inion-exchanged water and ultrasonically cleaned (at 100 kHz for 3minutes). Further, the objects to be polished were cleaned with runningion-exchanged water, and finally dried by spin drying.

(Preparation of Abrasive Slurry)

(1) Ce_(0.75)Zr_(0.25)O₂ Particle Slurry

A calcined product A (Ce_(0.75)Zr_(0.25)O₂ particles) was wet-pulverizedin water containing a dispersing agent (ammonium polyacrylate with aweight average molecular weight of 6000) using a bead mill, therebyproviding a Ce_(0.75)Zr_(0.25)O₂ particle slurry (Ce_(0.75)Zr_(0.25)O₂particles: 25 wt %) with a volume median diameter of 150 nm. Thecalcined product A was obtained by calcining uncalcinedCe_(0.75)Zr_(0.25)O₂ particles (ACTALYS 9320 manufactured by RhodiaJapan, Ltd.) at 1160° C. for 6 hours in a continuous kiln. The cerium(IV) compound and the zirconium (IV) compound were used as materials forthe calcined product A.

(2) CeO₂ Particle Slurry

A calcined product, i.e., CeCo₂ particles (with a purity of 99.9%manufactured by Baikowski Japan Co., Ltd.) were wet-pulverized in watercontaining a dispersing agent (ammonium polyacrylate with a weightaverage molecular weight of 6000) using a bead mill, thereby providing aCeO₂ particle slurry (CeO₂ particles: 40 wt %) with a volume mediandiameter of 130 nm. The cerium (IV) compound was used as a material forthe CeO₂ particles.

(3) Ce_(0.87)Zr_(0.13)O₂ Particle Slurry

A calcined product B (Ce_(0.87)Zr_(0.13)O₂ particles) was wet-pulverizedin water containing a dispersing agent (ammonium polyacrylate with aweight average molecular weight of 6000) using a bead mill, therebyproviding a Ce_(0.87)Zr_(0.13)O₂ particle slurry (Ce_(0.87)Zr_(0.13)O₂particles: 25 wt %) with a volume median diameter of 150 nm. Thecalcined product B was obtained by calcining uncalcinedCe_(0.87)Zr_(0.13)O₂ particles (manufactured by Rhodia Japan, Ltd.) at1100° C. for 6 hours in a continuous kiln. The cerium (IV) compound andthe zirconium (IV) compound were used as materials for the calcinedproduct B.

(4) Ce_(0.80)Zr_(0.20)O₂ Particle Slurry

A calcined product C (Ce_(0.80)Zr_(0.20)O₂ particles) was wet-pulverizedin water containing a dispersing agent (ammonium polyacrylate with aweight average molecular weight of 6000) using a bead mill, therebyproviding a Ce_(0.80)Zr_(0.20)O₂ particle slurry (Ce_(0.80)Zr_(0.20)O₂particles: 25 wt %) with a volume median diameter of 150 nm. Thecalcined product C was obtained by calcining uncalcinedCe_(0.80)Zr_(0.20)O₂ particles (ACTALYS 9315 manufactured by RhodiaJapan, Ltd.) at 1160° C. for 6 hours in a continuous kiln. The cerium(IV) compound and the zirconium (IV) compound were used as materials forthe calcined product C.

(5) Ce_(0.62)Zr_(0.38)O₂ Particle Slurry

A calcined product D (Ce_(0.62)Zr_(0.38)O₂ particles) was wet-pulverizedin water containing a dispersing agent (ammonium polyacrylate with aweight average molecular weight of 6000) using a bead mill, therebyproviding a Ce_(0.62)Zr_(0.38)O₂ particle slurry (Ce_(0.62)Zr_(0.38)O₂particles: 25 wt %) with a volume median diameter of 150 nm. Thecalcined product D was obtained by calcining uncalcinedCe_(0.62)Zr_(0.38)O₂ particles (ACTALYS 9330 manufactured by RhodiaJapan, Ltd.) at 1240° C. for 6 hours in a continuous kiln. The cerium(IV) compound and the zirconium (IV) compound were used as materials forthe calcined product D.

(6) Uncalcined Ce_(0.80)Zr_(0.20)O₂ Particle Slurry

Uncalcined Ce_(0.80)Zr_(0.29)O₂ particles (ACTALYS 9315 manufactured byRhodia Japan, Ltd.) were wet-pulverized in water containing a dispersingagent (ammonium polyacrylate with a weight average molecular weight of6000) using a bead mill, thereby providing an uncalcinedCe_(0.80)Zr_(0.20)O₂ particle slurry (Ce_(0.80)Zr_(0.20)O₂ particles: 25wt %) with a volume median diameter of 150 nm. The cerium (IV) compoundand the zirconium (IV) compound were used as materials for theuncalcined Ce_(0.80)Zr_(0.20)O₂ particles.

(7) Uncalcined Ce_(0.62)Zr_(0.38)O₂ Particle Slurry

Uncalcined Ce_(0.62)Zr_(0.38)O₂ (ACTALYS 9330 manufactured by RhodiaJapan, Ltd.) were wet-pulverized in water containing a dispersing agent(ammonium polyacrylate with a weight average molecular weight of 6000)using a bead mill, thereby providing an uncalcined Ce_(0.062)Zr_(0.38)O₂particle slurry (Ce_(0.62)Zr_(0.38)O₂ particles: 25 wt %) with a volumemedian diameter of 150 nm. The cerium (IV) compound and the zirconium(IV) compound were used as materials for the uncalcinedCe_(0.62)Zr_(0.38)O₂ particles.

(8) Ce_(0.74)Zr_(0.26)O₂ Particle Slurry

A calcined product E (Ce_(0.74)Zr_(0.26)O₂ particles) was wet-pulverizedin water containing a dispersing agent (ammonium polyacrylate with aweight average molecular weight of 6000) using a bead mill, therebyproviding a Ce_(0.74)Zr_(0.26)O₂ particle slurry (Ce_(0.74)Zr_(0.26)O₂particles: 25 wt %) with a volume median diameter of 150 nm. The cerium(III) compound and the zirconium (IV) compound were used as materialsfor the calcined product E.

The following is a detailed explanation of the method for preparing theCe_(0.74)Zr_(0.26)O₂ particle slurry.

First, 4280 g of 37.7 wt % cerium (III) nitrate solution and 1070 g of54.8 wt % zirconium (IV) nitrate solution were stirred and mixed in a 30L reactor. The pH of the resultant mixed solution was 1.26. Then, 10 Lof deionized water was added to the mixed solution.

Next, 3.8 mol/L ammonia water was added continuously at a supply rate of1.7 L/hr to the mixed solution to which the deionized water had beenadded. When the pH of this mixed solution reached 7.2, 1148 ml of 5.8mol/L hydrogen peroxide solution was added, and further ammonia waterwas added continuously to stabilize the pH, so that a coprecipitate ofcerium hydroxide and zirconium hydroxide was obtained. The total amountof ammonia water added was 2420 ml and the total amount of hydrogenperoxide solution (5.8 M) added was 1148 ml.

Then, the coprecipitate was filtered out using filter paper and cleanedwith deionized water. After calcining the cleaned product at 1130° C.for 2 hours, coarse particles were removed from the calcined productusing a 60-mesh filter. Subsequently, the calcined product E from whichthe coarse particles had been removed by screening was wet-pulverized,and then filtered out using a pleated filter with a filtration accuracyof 2 μm. Thus, the Ce_(0.74)Zr_(0.26)O₂ particle slurry was provided.

(Preparation of Polishing Liquid Composition)

The polishing liquid compositions were produced by mixing each of theslurries as prepared in the above manner, water, and nitric acid as a pHadjuster so that the abrasive grains, the dispersing agent, and thewater and pH adjuster were present in concentrations as shown in Tables1 to 3.

TABLE 1 Polishing Slurry Composition of Object to be rate Polishing No.polishing liquid composition wt % polished pH nm/min pad Ex. 1 (1)Ce_(0.75)Zr_(0.25)O₂ 1 100 Glass 6.3 454 Laminated Dispersing agent0.0025 base pad ※ Water and pH adjuster Residual material Comp. (2) CeO₂1 100 6.0 344 Ex. 1 Dispersing agent 0.0025 Water and pH adjusterResidual Ex. 2 (1) Ce_(0.75)Zr_(0.25)O₂ 5 100 6.3 1688 Dispersing agent0.0125 Water and pH adjuster Residual Comp. (2) CeO₂ 5 100 6.3 834 Ex. 2Dispersing agent 0.0125 Water and pH adjuster Residual Ex. 3 (1)Ce_(0.75)Zr_(0.25)O₂ 1 100 Glass 6.3 237 NP025 Dispersing agent 0.0025base Water and pH adjuster Residual material Comp. (2) CeO₂ 1 100 6.0155 Ex. 3 Dispersing agent 0.0025 Water and pH adjuster Residual Ex. 4(3) Ce_(0.87)Zr_(0.13)O₂ 5 100 6.1 196 Dispersing agent 0.0125 Water andpH adjuster Residual Ex. 5 (4) Ce_(0.80)Zr_(0.20)O₂ 5 100 6.2 216Dispersing agent 0.0125 Water and pH adjuster Residual Ex. 6 (1)Ce_(0.75)Zr_(0.25)O₂ 5 100 6.2 207 Dispersing agent 0.0125 Water and pHadjuster Residual Ex. 7 (5) Ce_(0.62)Zr_(0.38)O₂ 5 100 6.3 172Dispersing agent 0.0125 Water and pH adjuster Residual Comp. (2) CeO₂ 5100 6.3 167 Ex. 4 Dispersing agent 0.0125 Water and pH adjuster ResidualEx. 8 (1) Ce_(0.75)Zr_(0.25)O₂ 1 100 Synthetic 6.3 88 LaminatedDispersing agent 0.0025 quartz pad ※ Water and pH adjuster Residualwafer Comp. (2) CeO₂ 1 100 6.0 34 Ex. 5 Dispersing agent 0.0025 Waterand pH adjuster Residual Ex. 9 (1) Ce_(0.75)Zr_(0.25)O₂ 5 100 6.3 1472Dispersing agent 0.0125 Water and pH adjuster Residual Comp. (2) CeO₂ 5100 6.3 320 Ex. 6 Dispersing agent 0.0125 Water and pH adjuster Residual※ Laminated pad of IC1000 and suba400

TABLE 2 Polishing Slurry Composition of Object to be rate Polishing No.polishing liquid composition wt % polished pH nm/min pad Ex. 10 (1)Ce_(0.75)Zr_(0.25)O₂ 1 100 Synthetic 6.3 117 NP025 Dispersing agent0.0025 quartz Water and pH adjuster Residual wafer Comp. (2) CeO₂ 1 1006.0 71 Ex. 7 Dispersing agent 0.0025 Water and pH adjuster Residual Ex.11 (3) Ce_(0.87)Zr_(0.13)O₂ 5 100 6.1 798 Dispersing agent 0.0125 Waterand pH adjuster Residual Ex. 12 (4) Ce_(0.80)Zr_(0.20)O₂ 5 100 6.2 874Dispersing agent 0.0125 Water and pH adjuster Residual Ex. 13 (1)Ce_(0.75)Zr_(0.25)O₂ 5 100 6.3 562 Dispersing agent 0.0125 Water and pHadjuster Residual Ex. 14 (5) Ce_(0.62)Zr_(0.38)O₂ 5 100 6.3 787Dispersing agent 0.0125 Water and pH adjuster Residual Comp. (2) CeO₂ 5100 6.3 496 Ex. 8 Dispersing agent 0.0125 Water and pH adjuster ResidualEx. 15 (1) Ce_(0.75)Zr_(0.25)O₂ 1 100 TEOS 6.3 650 Laminated Dispersingagent 0.0025 film pad ※ Water and pH adjuster Residual Comp. (2) CeO₂ 1100 6.0 365 Ex. 9 Dispersing agent 0.0025 Water and pH adjuster ResidualEx. 20 (1) Ce_(0.75)Zr_(0.25)O₂ 1 100 HDP 6.3 725 Laminated Dispersingagent 0.0025 film pad ※ Water and pH adjuster Residual Comp. (2) CeO₂ 1100 6.0 400 Ex. 14 Dispersing agent 0.0025 Water and pH adjusterResidual ※ Laminated pad of IC1000 and suba400

TABLE 3 Polishing Slurry Composition of Object to be rate PolishingNumber of No. polishing liquid composition wt % polished pH nm/min padscratches Comp. (2) CeO₂ 1 100 Thermal 6.0 410 Laminated 12  Ex. 10Dispersing agent 0.0025 oxide pad ※ Water and pH adjuster Residual filmEx. 16 (3) Ce_(0.87)Zr_(0.13)O₂ 1 100 6.1 504 4 Dispersing agent 0.0025Water and pH adjuster Residual Ex. 17 (4) Ce_(0.80)Zr_(0.20)O₂ 1 100 6.2554 — Dispersing agent 0.0025 Water and pH adjuster Residual Ex. 18 (1)Ce_(0.75)Zr_(0.25)O₂ 1 100 6.3 665 3 Dispersing agent 0.0025 Water andpH adjuster Residual Ex. 19 (5) Ce_(0.62)Zr_(0.38)O₂ 1 100 6.2 538 8Dispersing agent 0.0025 Water and pH adjuster Residual Comp. (6)Ce_(0.80)Zr_(0.20)O₂ 1 100 6.1 101 — Ex. 11 Dispersing agent 0.0025Water and pH adjuster Residual Comp. (7) Ce_(0.62)Zr_(0.38)O₂ 1 100 6.176 — Ex. 12 Dispersing agent 0.0025 Water and pH adjuster Residual Comp.(8) Ce_(0.74)Zr_(0.26)O₂ 1 100 6.0 604 300 or more Ex. 13 Dispersingagent 0.025 Water and pH adjuster Residual ※ Laminated pad of IC1000 andsuba400

20 g of each slurry was dried in an atmosphere at 110° C. for 12 hours,and then the dried product was crushed in a mortar to provide a samplefor powder X-ray diffraction. Table 4 shows the results of the analysisof each sample by the powder X-ray diffraction method. The measurementconditions of the powder X-ray diffraction method were as follows.

(Measurement Conditions)

Apparatus: a powder X-ray diffractometer RINT2500VC manufactured byRigaku Corporation

X-ray generation voltage: 40 kV

Radiation: CU-Kα1 ray (λ=0.154050 nm)

Current: 120 mA

Scan speed: 10 degree/min

Measurement step: 0.02 degree/min

TABLE 4 First Second Third Fourth Slurry Composition of peak peak peakpeak Peak a₁ Peak a₂ (peak a₁/first (peak a₂/first Half-width Volumemedian No. abrasive grains (2θ) (2θ) (2θ) (2θ) (2θ) (2θ) peak) × 100(%)peak) × 100(%) of first peak diameter (nm) (1) Ce_(0.75)Zr_(0.25)O₂28.870° 33.471° 48.049° 57.012° — — 0 0 0.330° 150 100.0 27.0 49.5 37.3(2) CeO₂ 28.549° 33.077° 47.483° 56.342° — — 0 0 0.330° 130 100.0 28.152.7 39.6 (3) Ce_(0.87)Zr_(0.13)O₂ 28.729° 33.293° 47.824° 56.762° — — 00 0.347° 150 100.0 27.5 53.2 39.6 (4) Ce_(0.80)Zr_(0.20)O₂ 28.823°33.406° 47.986° 56.928° — — 0 0 0.300° 150 100.0 27.3 51.6 38.1 (5)Ce_(0.62)Zr_(0.38)O₂ 28.911° 33.467° 48.143° 57.084° — 29.813° 0 5.70.418° 150 100.0 24.5 49.0 30.5 5.7 (6) Ce_(0.80)Zr_(0.20)O₂ 28.820°33.500° 47.960° 57.060° — — 0 0 1.052° 150 (uncalcined) 100.0 23.4 43.427.7 (7) Ce_(0.62)Zr_(0.38)O₂ 29.080° 33.620° 48.740° 57.340° — — 0 00.991° 150 (uncalcined) 100.0 23.7 30.3 25.0 (8) Ce_(0.74)Zr_(0.26)O₂28.731° 33.273° 47.752° 56.717° — 29.831° 0 6.4 0.401° 150 100.0 36.174.1 18.5 6.4 Upper row: diffraction angle 2θ (each indicating the valueof a peak top) Lower row: peak area ratio (relative intensity when thefirst peak is defined as 100) (peak a₁/first peak) × 100 (%) indicates(height of peak top of peak a₁/height of peak top of first peak) × 100(%) (peak a₂/first peak) × 100 (%) indicates (height of peak top of peaka₂/height of peak top of first peak) × 100 (%)

The heights of the peak top of each peak, the half-width of the firstpeak, and the area of each peak were calculated from the measured powderX-ray diffraction spectrum using powder X-ray diffraction patternintegrated analysis software JADE (manufactured by MDI (Materials Data,Inc.)) that was included in the powder X-ray diffractometer. Thecalculation with this software was based on its instruction manual (Jade(Ver. 5) Software, Manual No. MJ13133E02, Rigaku Corporation).

When the peak derived from the cerium oxide and/or the peak derived fromthe zirconium oxide are present in the spectrum as shoulder peaks of thepeak derived from the composite oxide, e.g., the above software canseparate the peaks and determine the height of the peak top and the areaof each peak.

<Calculation Method of Polishing Rate>

1. Glass Base Material and Synthetic Quartz Wafer

First, a weight difference (g) of the object to be polished before andafter polishing was determined. Then, the polishing amount per unit timewas obtained by dividing the weight difference (g) by the density of theobject to be polished (the glass base material: 2.46 g/cm³ and thesynthetic quartz wafer: 2.20 g/cm³), the area of the surface of theobject to be polished (the glass base material: 30.04 cm² and thesynthetic quart wafer: 19.63 cm²), and the polishing time (min), so thatthe polishing rate (nm/min) was calculated.

2. TEOS Flm, Thermal Oxide Film, and HDP Film

The thicknessess of the TEOS film before and after polishing measuredwith a spectrometric film thickness measurement system (VM-1000manufactured by DAINIPPON SCREEN MFG. CO., LTD.). The polishing rate wascalculated from these values as expressed by the following equation. Thepolishing rate of the thermal oxide film or the HDP film also wasdetermined in the same manner.Polishing rate (nm/min)=(film thickness before polishing)−(filmthickness after polishing)

<Evaluation Method of Number of Scratches>

Object to be polished: a silicon wafer provided with a thermal oxidefilm

A 1000 nm thick silicon dioxide film was formed on a silicon wafer witha diameter of 5 cm (2 inches). The silicon dioxide film was obtained byexposing the silicon wafer to an oxygen gas or steam in an oxidationfurnace so that silicon in the silicon wafer was allowed to react withoxygen.

(Polishing Conditions)

Polishing test machine: a single-sided polishing machine MA-300 with aplaten diameter of 300 mm manufactured by Musashino Electronic Co., Ltd.

Polishing pad: a laminated pad of IC1000 (hard urethane pad) and suba400(nonwoven fabric pad) manufactured by NITTA HAAS INCORPORATED

Number of revolutions of platen: 90 r/min

Number of revolutions of carrier: 90 r/min (a forced drive system)

Supply rate of polishing liquid composition: 50 g/min (about 1.5mL/min/cm²)

Polishing time: 1 min

Polishing load: 300 g/cm² (a constant load applied by a weight)

Dress conditions: A brush was dressed with a diamond ring by supplyingion-exchanged water to the brush for 1 minute before polishing.

The objects to be polished were polished with each of the polishingliquid compositions under the above polishing conditions, and the numberof scratches was measured by the following method. The number of sampleswas 3. Table 3 shows the average of the number of scratches observed oneach of the polished objects.

In this case, a scratch is a flaw that has approximately a width of 20nm or more, a length of 50 μm or more, and a depth of 3 nm or more andcan be observed with MicroMax VMX-2100.

[Measurement Method of Number of Scratches]

Measurement equipment: MicroMax VMX-2100 manufactured by VISION PSYTECCO., LTD.

(MicroMax Measurement Conditions)

Light source: 2Sλ (250 W) and 3Pλ (250 W) (the amount of light: 100% forboth light sources)

Tilt angle: −9°

Magnification: maximum (the range of field of view: 1/35 of the entirearea of the polished surface)

Observed range: the entire area of the polished surface (the 2 inchdiameter wafer substrate provided with a thermal oxide film)

Iris: notch

Tables 1 to 3 show the polishing rates of polishing with each of thepolishing liquid compositions of Examples 1 to 20 and ComparativeExamples 1 to 14. As shown in Tables 1 to 3, comparing the example andthe comparative example having the same concentration of the abrasivegrains, it was confirmed that the polishing rate was higher with the useof the polishing liquid compositions of the examples than with the useof those of the comparative examples, regardless of whether the glassbase material, the synthetic quartz wafer, the TEOS film, the thermaloxide film, or the HDP film was polished.

As shown in Tables 3 and 4, when the thermal oxide film was polished, itwas confirmed that the number of scratches could be significantlyreduced with the use of the polishing liquid composition including thecomposite oxide particles in which both of (height of peak top of peaka₁/height of peak top of first peak)×100 and (height of peak top of peaka₂/height of peak top of first peak)×100 were 6.0% or less, compared tothe polishing liquid composition including the composite oxide particlesin which at least one of (height of peak top of peak a₁/height of peaktop of first peak)×100 and (height of peak top of peak a₂/height of peaktop of first peak)×100 was more than 6.0%.

Example 21

A polishing liquid composition was prepared to have the composition asshown in Table 5 in the following manner. First DHEG (CHELEST GAmanufactured by CHELEST CORPORATION) was mixed with ion-exchanged water.Then, the Ce_(0.87)Zr_(0.13)O₂ particle slurry was added to theresultant mixed solution while stirring the mixed solution. Moreover,the pH of this mixed solution was adjusted to 6.2 with a 10% ammoniaaqueous solution. Thus, the polishing liquid composition was prepared.

Examples 22 to 24

Polishing liquid compositions were prepared to have the compositions asshown in Table 5 in the same manner as Example 21 except that theCe_(0.80)Zr_(0.20)O₂ particle slurry, the Ce_(0.75)Zr_(0.25)O₂ particleslurry, or the Ce_(0.62)Zr_(0.38)O₂ particle slurry was used instead ofthe Ce_(0.87)Zr_(0.13)O₂ particle slurry.

Example 25

A polishing liquid composition was prepared to have the composition asshown in Table 5 in the following manner. First, EDTA-2NH₄ (manufacturedby DOJINDO LABORATORIES) was mixed with ion-exchanged water. Then, theCe_(0.75)Zr_(0.25)O₂ particle slurry was added to the resultant mixedsolution while stirring the mixed solution. Moreover, the pH of thismixed solution was adjusted to 6.2 with a 10% ammonia aqueous solution.Thus, the polishing liquid composition was prepared.

Example 26

A polishing liquid composition was prepared to have the composition asshown in Table 5 in the following manner. First, L-aspartic acid(manufactured by Wako Pure Chemical Industries, Ltd.) was mixed withion-exchanged water. Then, 10% ammonia water was added to the resultantmixed solution while stirring the mixed solution, so that the L-asparticacid was dissolved. Moreover, the Ce_(0.75)Zr_(0.25)O₂ particle slurrywas added, and finally the pH of this mixed solution was adjusted to 6.0with 10% ammonia water. Thus, the polishing liquid composition wasprepared.

Comparative Example 15

A polishing liquid composition as shown in Table 5 was prepared in thesame manner as Example 21 except that the CeO₂ particle slurry was usedinstead of the Ce_(0.87)Zr_(0.13)O₂ particle slurry, and the content ofDHEG (CHELEST GA manufactured by CHELEST CORPORATION) was changed.

Reference Example 1

A polishing liquid composition having the composition as shown in Table5 was prepared in the same manner as Example 21. TheCe_(0.75)Zr_(0.25)O₂ particle slurry was added to ion-exchanged waterwhile stirring the ion-exchanged water. Moreover, the pH of this mixedsolution was adjusted to 6.2 with 1% nitric acid. Thus, the polishingliquid composition was prepared.

TABLE 5 Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Comp. Ex. 15 Ref. Ex.1 (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %)Ce_(0.87)Zr_(0.13)O₂ particles 1.0 — — — — — — — Ce_(0.80)Zr_(0.20)O₂particles — 1.0 — — — — — — Ce_(0.75)Zr_(0.25)O₂ particles — — 1.0 — 1.01.0 — 1.0 Ce_(0.62)Zr_(0.38)O₂ particles — — — 1.0 — — — — CeO₂particles — — — — — — 1.0 — DHEG 1.6 1.5 1.5 1.3 — — 1.3 — EDTA — — — —0.22 — — — L-aspartic acid — — — — — 0.9 — — Dispersing agent^(※1)0.0025 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025 Ion-exchangedwater and Residual Residual Residual Residual Residual Residual ResidualResidual pH adjuster Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0100.0 ^(※1)Ammonium polyacrylate added during the preparation ofcomposite oxide particle slurry

Evaluation Sample

As an evaluation sample, a commercially available wafer for evaluatingthe CMP characteristics (STI MIT 864 with a diameter of 200 mm) wasprepared. This evaluation sample will be described with reference toFIGS. 4A to 5A to 5D. FIGS. 4A and 5A to 5D are partially enlargedcross-sectional views of the evaluation sample. FIG. 4B is a top view ofthe evaluation sample and FIG. 4C is a partially enlarged view of FIG.4B. As shown in FIG. 4A, the evaluation sample includes a siliconsubstrate and a silicon nitride film (referred to as a “Si₃N₄ film” inthe following) with a thickness of 150 nm disposed on the siliconsubstrate. The Si₃N₄ film is formed by the CVD method. This laminate hasgrooves having a depth of 500 nm (150 nm+350 nm). A silicon oxide film(referred to as a “HDP film” in the following) with a thickness of 600nm is disposed on the Si₃O₄ film. The HDP film is formed by the HDP-CVD(high-density plasma chemical vapor deposition) method. As shown in FIG.4B, the plane of the HDP film is divided into 61 regions (20 mm×20 mm),and each of the regions is further divided into 25 small regions (4 mm×4mm) (FIG. 4C). In FIG. 4B, the solid black region (referred to as a“center” in the following) is where the thickness is measured, as willbe described later. In FIG. 4C, each of the numbers 20, 50, 90, and 100of D20, D50, D90, and D100 indicates the proportion of the entire areaof the convex portions to the area of the small region shown in a planview (i.e., the surface density of the convex portion). FIGS. 5A to 5Dare partially enlarged cross-sectional views of these small regions. Asshown in each of the drawings, D20 (FIG. 5A) includes a linearconcavo-convex pattern of a convex portion with a width of 20 μm and aconcave portion with a width of 80 μm. D50 (FIG. 5B) includes a linearconcavo-convex pattern of a convex portion with a width of 50 μm and aconcave portion with a width of 50 μm. D90 (FIG. 5C) includes a linearconcavo-convex pattern of a convex portion with a width of 90 μm and aconcave portion with a width of 10 μm. D100 (FIG. 5D) includes noconcavo-convex pattern, since the convex portions make up the whole ofthe small region.

(Polishing Conditions)

Polishing test machine: a single-sided polishing machine LP-541 with aplaten diameter of 540 mm manufactured by Lapmaster SFT Corp.

Polishing pad: IC-1000/Suba400 manufactured by NITTA HAAS INCORPORATED

Number of revolutions of platen: 100 rpm

Number of revolutions of head: 110 rpm (the rotation direction is thesame as that of the platen)

Polishing load: 30 kPa (a set value)

Supply of polishing liquid composition: 200 mL/min (0.6 g/(cm²min))

Using the polishing liquid compositions as shown in Table 5, theevaluation samples were polished under the above polishing conditions.After polishing the objects to be polished, they were cleaned withrunning ion-exchanged water, and then immersed in ion-exchange water andultrasonically cleaned (at 100 kHz for 3 minutes). Further, the objectsto be polished were cleaned with running ion-exchanged water, andfinally dried by spin drying.

The end of polishing was determined by utilizing torque measurement. Inthis measurement, the end of polishing is determined by changes infriction coefficient between the surface to be polished and thepolishing pad. Actually, the end of polishing was determined by changesin driving current of the platen on which the object to be polished wasplaced rather than by measuring the friction coefficient. In the earlystage of polishing, only the HDP film came into contact with thepolishing pad. In the final stage of polishing, however, the Si₃N₄ filmwas exposed, and thus the friction coefficient was changed. Therefore,the driving current value of the platen was also changed. When the Si₃N₄film was exposed, the driving current value became saturated. The timeat which the driving current value reached saturation was identified asan end point (EP) of polishing, and the polishing was performed for 30more seconds and finished (see FIG. 7). Accordingly, the polishing timewas expressed by (the time between the start of polishing and the EP+30)seconds. FIG. 7 shows an example of changes in the driving current valueof the platen over time. The polishing times were 72 seconds in Example21, 93 seconds in Example 22, 105 seconds in Example 23, 131 seconds inExample 24, 85 seconds in Example 25, 87 seconds in Example 26, 150seconds in Comparative Example 15, and 85 seconds in Reference Example1.

The remaining thickness of the center of the polished evaluation samplewas measured with a spectrometric film thickness measurement system(VM-1000 manufactured by DAINIPPON SCREEN MFG. CO., LTD.). FIG. 6 is aconceptual diagram of the polished evaluation sample. As shown in FIG.6, three types of remaining thicknesses were measured: the thickness(t1) of the HDP film in the convex portion; the thickness (t2) of theSi₃N₄ film in the convex portion; and the thickness (t3) of the HDP filmin the concave portion.

From the measurement results, the flatness was evaluated based on thecriteria as shown in Table 7. Table 6 shows the evaluation results. Themarks (◯) and (X) in Table 6 are based on the criteria of Table 7.Moreover, the “step height” in Tables 7 and 6 indicates a difference inthickness between the convex portion and the concave portion afterpolishing, and can be calculated by the following formula using thethickness (t1) of the HDP film in the convex portion, the thickness (t2)of the Si₃N₄ film in the convex portion, and the thickness (t3) of theHDP film in the concave portion (see FIG. 6). All the thicknesses of thefollowing formula are in nanometers (nm).Step Height={Si₃N₄ film thickness (convex portion)+HDP film thickness(convex portion)+350}−HDP film thickness (concaveportion)=(t2+t1+350)−t3

In general, the remaining thickness in the convex portion increases asthe surface density of the convex portion becomes larger (i.e., thesurface density of the concave portion becomes smaller), while theconcave portion is ground more easily and a dishing phenomenon is morelikely to occur as the surface density of the convex portion becomessmaller (i.e., the surface density of the concave portion becomeslarger). Thus, the evaluation of whether or not the polishing wasperformed sufficiently was based on the measurement results of D90 andD100 (including no concave portion), and the evaluation of the effect ofsuppressing the dishing phenomenon was based on the measurement resultsof D20.

TABLE 6 Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Comp. Ex. 15 Ref. Ex.1 D100 Convex HDP    95^(※1)  7  0  58  0  42  0  0 portion ◯ ◯ ◯ ◯ ◯ ◯◯ ◯ Si₃N₄ 149 150 140 150 144 148 150  0 ◯ ◯ ◯ ◯ ◯ ◯ ◯ X D90 Convex HDP 41  0  0  39  0  50  19  0 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Si₃N₄ 150 149 139150 144 148 150  0 ◯ ◯ ◯ ◯ ◯ ◯ ◯ X Concave HDP 545 502 481 537 477 552522 340 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ X Step Height^(※2)  −4  −3  8  2  17  −3 2  10 ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ D50 Convex HDP  17  0  0  38  0  10  8  0 portion◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Si₃N₄ 150 133 137 150 145 143 150  0 ◯ ◯ ◯ ◯ ◯ ◯ ◯ XConcave HDP 521 500 465 545 486 487 521 249 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ X StepHeight  −4 −17  22 −8  9  17  −8 101 ◯ ◯ ◯ ◯ ◯ ◯ ◯ X D20 Convex HDP  0 0  0  0  0  0  0  0 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Si₃N₄ 131 123 128 124 134120 128  0 ◯ ◯ ◯ ◯ ◯ ◯ ◯ X Concave HDP 489 483 470 501 475 436 492  77portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ X Step Height  −7 −10  8  −3  9  34 −14 273 ◯ ◯ ◯◯ ◯ ◯ ◯ X Polishing time (sec)  72  93 105 131  85  87 150  85 ^(※1)Allthe numerical values of D100, D90, D50, and D20 are in nanometers (nm).^(※2)The step height is determined by calculation of HDP film thickness(convex) + SiN film thickness (convex) + 350 − HDP film thickness(concave)

TABLE 7 ◯ X Convex HDP less than 100 nm 100 nm or more portion Si₃N₄ 120nm or more less than 120 nm Concave HDP 400 nm or more less than 400 nmportion Step Height less than 50 nm 50 nm or more

As shown in Table 6, in each of the evaluation samples polished with thepolishing liquid compositions of Examples 21 to 26, the thickness (t1)of the HDP film in the convex portion, the thickness (t2) of the Si₃N₄film in the convex portion, the thickness (t3) of the HDP film in theconcave portion, and the step height in all the regions met the criteriarepresented by ◯ in Table 7. Therefore, it was confirmed that thepolishing liquid compositions of Examples 21 to 26 were capable ofsuppressing the occurrence of dishing, achieving sufficient polishing,and providing a polished surface with high flatness. Moreover, thepolishing time was shorter with the use of the polishing liquidcompositions of Examples 21 to 26 than with the use of that ofComparative Example 15.

In the evaluation sample polished with the polishing liquid compositionof Comparative Example 15, the thickness (t1) of the HDP film in theconvex portion, the thickness (t2) of the Si₃N₄ film in the convexportion, the thickness (t3) of the HDP film in the concave portion, andthe step height in all the regions met the criteria represented by ◯ inTable 7. However, the polishing times was longer with the use of thepolishing liquid composition of Comparative Example 15 than with the useof those of Example 21 and Reference Example 1.

When the polishing liquid composition of Reference Example 1 was used,although the polishing time was shorter than in the case of thepolishing liquid compositions of Examples 22, 23, 24, and 26, dishingoccurred in most regions due to excessive polishing, so that theflatness of the polished surface had a problem.

The above evaluation results confirmed that when an uneven surface waspolished with the polishing liquid composition including specificcomposite oxide particles containing cerium and zirconium, thedispersing agent, the water-soluble organic compound, and the aqueousmedium, a polished surface with excellent flatness could be formed in ashort time.

Example 27

A polishing liquid composition was prepared to have the composition asshown in Table 8 in the following manner. First, a 30 wt % aqueoussolution of ammonium polyacrylate (degree of neutralization: 65 mol %,weight average molecular weight: 6000) was mixed with ion-exchangedwater. Then, the Ce_(0.87)Zr_(0.13)O₂ particle slurry was added to theresultant mixed solution while stirring the mixed solution. Moreover,the pH of this mixed solution was adjusted to 6.2 with a 10% ammoniaaqueous solution. Thus, the polishing liquid composition was prepared.

Examples 28 to 30

Polishing liquid compositions were prepared to have the compositions asshown in Table 8 in the same manner as Example 27 except that theCe_(0.80)Zr_(0.20)O₂ particle slurry, the Ce_(0.75)Zr_(0.25)O₂ particleslurry, or the Ce_(0.62)Zr_(0.38)O₂ particle slurry was used instead ofthe Ce_(0.87)Zr_(0.13)O₂ particle slurry.

Example 31

A polishing liquid composition was prepared to have the composition asshown in Table 8 in the following manner: First, a 40 wt % aqueoussolution of ammonium polyacrylate (degree of neutralization: 20 mol %,weight average molecular weight: 2000) was mixed with ion-exchangedwater. Then, the Ce_(0.75)Zr_(0.25)O₂ particle slurry was added to theresultant mixed solution while stirring the mixed solution. Moreover,the pH of this mixed solution was adjusted to 5.0 with a 10% ammoniaaqueous solution. Thus, the polishing liquid composition was prepared.

Example 32

A polishing liquid composition was prepared to have the composition asshown in Table 8 in the following manner. First a 43 wt % aqueoussolution of a sodium salt of a copolymer of acrylic acid and AMPS(2-acrylamide-2methylpropanesulfonic acid) (ARON A-6017 with a weightaverage molecular weight of 6000 manufactured by TOAGOSEI CO., LTD.) wasmixed with ion-exchanged water. Then, the Ce_(0.87)Zr_(0.13)O₂ particleslurry was added to the resultant mixed solution while stirring themixed solution. Moreover, the pH of this mixed solution was adjusted to6.5 with 1% nitric acid. Thus, the polishing liquid composition wasprepared.

Example 33

A polishing liquid composition was prepared to have the composition asshown in Table 8 in the following manner. First, an ammonium salt of acopolymer acrylic acid and maleic acid (degree of neutralization: 90 mol%, weight average molecular weight: 6000) was mixed with ion-exchangedwater. Then, the Ce_(0.75)Zr_(0.25)O₂ particle slurry was added to theresultant mixed solution while stirring the mixed solution. Moreover,the pH of this mixed solution was adjusted to 6.0 with 1% nitric acid.Thus, the polishing liquid composition was prepared.

Comparative Example 16

A polishing liquid composition having the composition as shown in Table8 was prepared in the same manner as Example 27 except that the CeO₂particle slurry was used instead of the Ce_(0.87)Zr_(0.13)O₂ particleslurry.

Reference Example 2

A polishing liquid composition having the composition as shown in Table8 was prepared in the same manner as Example 27. TheCe_(0.75)Zr_(0.25)O₂ particle slurry was added to ion-exchanged waterwhile stirring the ion-exchanged water. Moreover, the pH of this mixedsolution was adjusted to 6.2 with 1% nitric acid. Thus, the polishingliquid composition was prepared.

Comparative Example 17

A polishing liquid composition having the composition as shown in Table8 was prepared in the same manner as Example 31 except that the CeO₂particle slurry was used instead of the Ce_(0.75)Zr_(0.25)O₂ particleslurry, and the content of the water-soluble acrylic acid-based polymerwas changed.

Comparative Example 18

A polishing liquid composition having the composition as shown in Table8 was prepared in the same manner as Example 32 except that the CeO₂particle slurry was used instead of the Ce_(0.87)Zr_(0.13)O₂ particleslurry, and the contents of the composite oxide particles and thewater-soluble acrylic acid-based polymer were changed.

TABLE 8 Comp. Ref. Comp. Comp. Ex. 27 Ex. 28 Ex. 29 Ex. 30 Ex. 31 Ex. 32Ex. 33 Ex. 16 Ex. 2 Ex. 17 Ex. 18 (wt %) (wt %) (wt %) (wt %) (wt %) (wt%) (wt %) (wt %) (wt %) (wt %) (wt %) Ce_(0.87)Zr_(0.13)O₂ 1.0 — — — —1.0 — — — — — particles Ce_(0.80)Zr_(0.20)O₂ — 1.0 — — — — — — — — —particles Ce_(0.75)Zr_(0.25)O₂ — — 1.0 — 1.5 — 1.0 — 1.0 — — particlesCe_(0.62)Zr_(0.38)O₂ — — — 1.0 — — — — — — — particles CeO₂ particles —— — — — — — 1.0 — 1.5 1.0 Ammonium 0.80 0.70 0.70 0.70 — — — 0.55 — — —polyacrylate (Mw 6000) Ammonium — — — — 0.21 — — — — 0.20 — polyacrylate(Mw 2000) Acrylic — — — — — 1.3 — — — — 1.1 acid-AMPS copolymer Acrylic— — — — — — 0.6 — — — — acid-maleic acid copolymer Dispersing 0.00250.0025 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025agent^(※1) Ion-exchanged Residual Residual Residual Residual ResidualResidual Residual Residual Residual Residual Residual water and pHadjuster Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0100.0 100.0 ^(※1)Ammonium polyacrylate added during the preparation ofcomposite oxide particle slurry

(Evaluation Sample)

As an evaluation sample, a commercially available wafer for evaluatingthe CMP characteristics (STI MIT 864 with a diameter of 200 nm), whichhad been used for the evaluations of Examples 21 to 26, ComparativeExample 15, and Reference Example 1, was prepared.

(Polishing Conditions)

The polishing conditions were the same as these for the evaluations ofExamples 21 to 26, Comparative Example 15, and Reference Example 1. Theend of polishing was determined by utilizing the torque measurement.

The polished evaluation sample was cleaned and dried in the same manneras that for the evaluations of Examples 21 to 26, Comparative Example15, and Reference Example 1.

The polishing times were 78 seconds in Example 27, 76 seconds in Example28, 82 seconds in Example 29, 90 seconds in Example 30, 72 seconds inExample 31, 93 seconds in Example 32, 99 seconds in Example 33, 102seconds in Comparative Example 16, 85 seconds in Reference Example 2,105 seconds in Comparative Example 17, and 128 seconds in ComparativeExample 18.

The remaining thickness of the center of the polished evaluation samplewas measured with a spectrometric film thickness measurement system(VM-1000 manufactured by DAINIPPON SCREEN MFG. CO., LTD.). FIG. 6 is aconceptual diagram of the polished evaluation sample. As shown n FIG. 6,three types of remaining thicknesses were measured: the thickness (t1)of the HDP film in the convex portion; the thickness (t2) of the Si₃N₄film in the convex portion; and the thickness (t3) of the HDP film inthe concave portion.

From the measurement results, the flatness was evaluated based on thecriteria as shown in Table 7. Table 9 shows the evaluation results. Themarks (◯ and X) in Table 9 are based on the criteria of Table 7.

TABLE 9 Comp. Ref. Comp. Comp. Ex. 27 Ex. 28 Ex. 29 Ex. 30 Ex. 31 Ex. 32Ex. 33 Ex. 16 Ex. 2 Ex. 17 Ex. 18 D100 Convex HDP    0^(※1)  0  0  95  0 0  50  0  0  0  92 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Si₃N₄ 150 144 148 149145 143 149 146  0 150 147 ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X ◯ ◯ D90 Convex HDP  0  0 14  77  0  0  86  0  0  0  19 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Si₃N₄ 149142 150 150 146 141 149 145  0 150 148 ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X ◯ ◯ Concave HDP484 488 503 570 481 496 571 485 340 493 528 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X ◯◯ Step Height^(※2)  15  4  11  7  15  −4  14  10  10  7  2 ◯ ◯ ◯ ◯ ◯ ◯ ◯◯ ◯ ◯ ◯ D50 Convex HDP  0  0  0  0  0  0  10  0  0  20  9 portion ◯ ◯ ◯◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Si₃N₄ 149 140 147 141 143 140 149 141  0 150 147 ◯ ◯ ◯ ◯◯ ◯ ◯ ◯ X ◯ ◯ Concave HDP 480 486 491 486 483 487 507 479 249 509 517portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X ◯ ◯ Step Height  19  4  4  5  10  3  2  12 101 11 −11 ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X ◯ ◯ D20 Convex HDP  0  0  0  51  0  0  0  0  0 0  0 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Si₃N₄ 138 121 136 149 133 123 127114  0 138 132 ◯ ◯ ◯ ◯ ◯ ◯ ◯ X X ◯ ◯ Concave HDP 447 445 469 558 470 428448 415  77 466 467 portion ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X ◯ ◯ Step Height  41  26 17  −7  13  45  30  49 273  22  15 ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ X ◯ ◯ Polishing time(sec)  78  76  82  90  72  93  99 102  85 105 128 ^(※1)All the numericalvalues of D100, D90, D50, and D20 are in nanometers (nm). ^(※2)The stepheight is determined by calculation of HDP film thickness (convex) + SiNfilm thickness (convex) + 350 − HDP film thickness (concave)

As shown in Table 9, in each of the evaluation samples polished with thepolishing liquid compositions of Examples 27 to 33, the thickness (t1)of the HDP film in the convex portion, the thickness (t2) of the Si₃N₄film in the convex portion, the thickness (t3) of the HDP film in theconcave portion, and the step height in all the regions met the criteriarepresented by ◯ in Table 7. Therefore, it was confirmed that thepolishing liquid compositions of Examples 27 to 33 were capable ofsuppressing the occurrence of dishing, achieving sufficient polishing,and providing a polished surface with high flatness. Moreover, thepolishing time was shorter with the use of the polishing liquidcompositions of Examples 27 to 33 than with the use of those ofComparative Examples 16, 17, and 18.

In the evaluation sample polished with the polishing liquid, compositionof Comparative Example 16, except for the thickness (t2) of the Si₃N₄film in the convex portion in D20, the thickness (t1) of the HDP film inthe convex portion, the thickness (t2) of the Si₃N₄ film in the convexportion, the thickness (t3) of the HDP film in the concave portion, andthe step height in all other regions met the criteria represented by ◯in Table 7. In each of the evaluation samples polished with thepolishing liquid compositions of Comparative Examples 17 and 18, thethickness (t1) of the HDP film in the convex portion, the thickness (t2)of the Si₃N₄ film in the convex portion, the thickness (t3) of the HDPfilm in the concave portion, and the step height in all the regions metthe criteria represented by ◯ in Table 7. However, the polishing timewas longer with the use of the polishing liquid compositions ofComparative Examples 16, 17, and 18 than with the use of those ofExamples 27 to 33 and Reference Example 2.

When the polishing liquid composition of Reference Example 2 was used,although the polishing time was shorter than in the case of thepolishing liquid compositions of Examples 30, 32, and 33, dishingoccurred in most regions due to excessive polishing, as shown in Table8, so that the flatness of the polished surface had a problem.

The above evaluation results confirmed that when an uneven surface waspolished with the polishing liquid composition including specificcomposite oxide particles containing cerium and zirconium, thedispersing agent, the water-soluble acrylic acid-based polymer, and theaqueous medium, a polished surface with excellent flatness could beformed in a short time.

INDUSTRIAL APPLICABILITY

The use of an example of the polishing liquid composition of thisembodiment can polish the object to be polished at a higher speed andreduce scratches. Therefore, the polishing liquid composition of thisembodiment is suitable for the polishing of an oxide film (e.g., asilicon oxide film) constituting a semiconductor device, the basematerial of a chemically tempered glass substrate such as analuminosilicate glass substrate, the base material of a crystallizedglass substrate such as a glass-ceramic substrate, the base material ofa synthetic quartz glass substrate used as a photomask substrate or alens material for stepper, or a glass surface or the like of a liquidcrystal display panel.

The use of an example of the polishing liquid composition of the presentinvention can provide a polished surface with excellent flatness in ashort time. Therefore, the polishing liquid composition of the presentinvention is useful as a polishing liquid composition used in themanufacturing process of various semiconductor devices, particularlyuseful for the manufacture of IC and LSI.

The invention claimed is:
 1. A polishing method comprising: supplying apolishing liquid composition between an object to be polished and apolishing pad; and polishing the object to be polished by moving thepolishing pad relative to the object to be polished while the object tobe polished is in contact with the polishing pad, the polishing liquidcomposition comprising: composite oxide particles containing cerium andzirconium; a dispersing agent; and an aqueous medium, wherein a powderX-ray diffraction spectrum of the composite oxide particles obtained byCuKα1 ray, where λ=0.154050 nm, irradiation includes a first peak havinga peak top in a diffraction angle 2θ range of 28.61 to 29.67°, wherein θis a Bragg angle, a second peak having a peak top in a diffraction angle2θ range of 33.14 in 34.53°, a third peak having a peak top in adiffraction angle 2θ range of 47.57 to 49.63°, and a fourth peak havinga peak top in a diffraction angle 2θ range of 56.45 to 58.91°, wherein ahalf-width of the first peak is 0.8° or less, and wherein when there isat least one peak of a peak a₁ derived from a cerium oxide and a peak a₂derived from a zirconium oxide in the powder X-ray diffraction spectrum,both heights of peak tops of the peaks a₁, a₂ are 0% of a height of thepeak top of the first peak, where the peak top of the peak a₁ lies in adiffraction angle 2θ range of 28.40 to 28.59° and the peak top of thepeak a₂ lies in a diffraction angle 2θ range of 29.69 to 31.60°.
 2. Amethod for manufacturing a glass substrate comprising: polishing atleast one of two principal surfaces of a base material of a glasssubstrate with a polishing liquid composition, the polishing liquidcomposition comprising: composite oxide particles containing cerium andzirconium; a dispersing agent; and an aqueous medium, wherein a powderX-ray diffraction spectrum of the composite oxide particles obtained byCuKα1 ray, where λ=0.154050 nm, irradiation includes a first peak havinga peak top in a diffraction angle 2θ range of 28.61 to 29.67°, wherein θis a Bragg angle, a second peak having a peak top in a diffraction angle2θ range of 33.14 to 34.53°, a third peak having a peak top in adiffraction angle 2θ range of 47.57 to 49.63°, and a fourth peak havinga peak top in a diffraction angle 2θ range of 56.45 to 58.91°, wherein ahalf-width of the first peak is 0.8° or less, and wherein when there isat least one peak of a peak a₁ derived from a cerium oxide and a peak a₂derived from a zirconium oxide in the powder X-ray diffraction spectrum,both heights of peak tops of the peaks a₁, a₂ are 0% of a height of thepeak top of the first peak, where the peak top of the peak a₁ lies in adiffraction angle 2θ range of 28.40 to 28.59° and the peak top of thepeak a₂ lies in a diffraction angle 2θ range of 29.69 to 31.60°.
 3. Themethod for manufacturing a glass substrate according to claim 2, whereinan area of the second peak is 10 to 50% of an area of the first peak, anarea of the third peak is 35 to 75% of the area of the first peak, andan area of the fourth peak is 20 to 65% of the area of the first peak.4. The method for manufacturing a glass substrate according to claim 2,wherein a volume median diameter of the composite oxide particles is 30to 1000 nm.
 5. The method for manufacturing a glass substrate accordingto claim 2, further comprising a water-soluble organic compound.
 6. Themethod for manufacturing a glass substrate according to claim 5, whereinthe water-soluble organic compound includes an amphoteric water-solubleorganic compound having a molecular weight of 1,000 or less.
 7. Themethod for manufacturing a glass substrate according to claim 5, whereinthe water-soluble organic compound includes a water-soluble acrylicacid-based polymer.
 8. The method for manufacturing a glass substrateaccording to claim 7, wherein the water-soluble acrylic acid-basedpolymer is polyacrylic acid having a constitutional unit derived from atleast one monomer selected from the group consisting of acrylic acid anda non-metallic salt of acrylic acid.
 9. The method for manufacturing aglass substrate according to claim 5, wherein 0.1 to 8 wt % of thecomposite oxide particles, 0.0005 to 0.5 wt % of the dispersing agent,and 0.02 to 15 wt % of the water-soluble organic compound are includedin the total amount of the polishing liquid composition.
 10. A methodfor manufacturing a semiconductor device comprising: a thin filmformation process of forming a thin film on one principal surface sideof a semiconductor substrate; and a polishing process of polishing thethin film with a polishing liquid composition, the polishing liquidcomposition comprising: composite oxide particles containing cerium andzirconium; a dispersing agent; and an aqueous medium, wherein a powderX-ray diffraction spectrum of the composite oxide particles obtained byCuKα1 ray, where λ=0.154050 nm, irradiation includes a first peak havinga peak top in a diffraction angle 2θ range of 28.61 to 29.67°, wherein θis a Bragg angle, a second peak having a peak top in a diffraction angle2θ range of 33.14 to 34.58°, a third peak having a peak top in adiffraction angle 2θ range of 47.57 to 49.63°, and a fourth peak havinga peak top in a diffraction angle 2θ range of 56.45 to 58.91°; wherein ahalf width of the first peak is 0.8° or less, and wherein when there isat least one peak of a peak a₁ derived from a cerium oxide and a peak a₂derived from a zirconium oxide in the powder X-ray diffraction spectrum,both heights of peak tops of the peaks a₁, a₂ are 0% of a height of thepeak top of the first peak, where the peak top of the peak a₁ lies in adiffraction angle 2θ range of 28.40 to 28.59° and the peak top of thepeak a₂ lies in a diffraction angle 2θ range of 29.69 to 31.60°.
 11. Themethod for manufacturing a semiconductor device according to claim 10,wherein an area of the second peak is 10 to 50% of an area of the firstpeak, an area of the third peak is 35 to 75% of the area of the firstpeak, and an area of the fourth peak is 20 to 65% of the area of thefirst peak.
 12. The method for manufacturing a semiconductor deviceaccording to claim 10, wherein a volume median diameter of the compositeoxide particles is 30 to 1000 nm.
 13. The method for manufacturing asemiconductor device according to claim 10, further comprising awater-soluble organic compound.
 14. The method for manufacturing asemiconductor device according to claim 13, wherein the water solubleorganic compound includes an amphoteric water-soluble organic compoundhaving a molecular weight of 1,000 or less.
 15. The method formanufacturing a semiconductor device according to claim 13, wherein thewater-soluble organic compound includes a water-soluble acrylicacid-based polymer.
 16. The method for manufacturing a semiconductordevice according to claim 15, wherein the water-soluble acrylicacid-based polymer is polyacrylic acid having a constitutional unitderived from at least one monomer selected from the group consisting ofacrylic acid and a non-metallic salt of acrylic acid.
 17. The method formanufacturing a semiconductor device according to claim 13, wherein 0.1to 8 wt % of the composite oxide particles, 0.0005 to 0.5 wt % of thedispersing agent, and 0.02 to 15 wt % of the water-soluble organiccompound are included in the total amount of the polishing liquidcomposition.